Samacheer Kalvi 10th Maths Exercise 1.4 Solutions

10th Maths Exercise 1.4 solutions (Chapter 1 Relations and Functions) with step-by-step answers for all 32 questions, as per the 2026-27 Samacheer Kalvi textbook.

Answers at a glance29 answers · full steps below
  1. Q1 (i)Not a function (fails the vertical line test — a vertical line meets the curve at two points).
  2. Q1 (ii)It is a function (passes the vertical line test).
  3. Q1 (iii)Not a function (fails the vertical line test).
  4. Q1 (iv)It is a function (passes the vertical line test).
  5. Q2 (i)f={(2,0),(4,1),(6,2),(10,4),(12,5)}f=\{(2,0),(4,1),(6,2),(10,4),(12,5)\}
  6. Q2 (ii)x2461012f(x)01245\begin{array}{|c|c|c|c|c|c|}\hline x & 2 & 4 & 6 & 10 & 12\\\hline f(x) & 0 & 1 & 2 & 4 & 5\\\hline\end{array}
  7. Q2 (iii)Arrow diagram: 2→0,  4→1,  6→2,  10→4,  12→52\to 0,\; 4\to 1,\; 6\to 2,\; 10\to 4,\; 12\to 5 (the element 9∈B9\in B has no pre-image).
  8. Q2 (iv)Plot the points (2,0),(4,1),(6,2),(10,4),(12,5)(2,0),(4,1),(6,2),(10,4),(12,5); they lie on a straight line.
  9. Q3 (i)Arrow diagram: 1→2,  2→2,  3→2,  4→3,  5→41\to2,\;2\to2,\;3\to2,\;4\to3,\;5\to4.
  10. Q3 (ii)x12345f(x)22234\begin{array}{|c|c|c|c|c|c|}\hline x & 1 & 2 & 3 & 4 & 5\\\hline f(x) & 2 & 2 & 2 & 3 & 4\\\hline\end{array}
  11. Q3 (iii)Plot the points (1,2),(2,2),(3,2),(4,3),(5,4)(1,2),(2,2),(3,2),(4,3),(5,4).
  12. Q6 (i)Range of f={1,8,27,64}f=\{1,8,27,64\}
  13. Q6 (ii)ff is a one-one and into function.
  14. Q7 (i)ff is bijective (one-one and onto).
  15. Q7 (ii)ff is not bijective (it is neither one-one nor onto).
  16. Q8a=1a=1 or a=−1a=-1, and b=1b=1
  17. Q9 (i)f(3)=5f(3)=5
  18. Q9 (ii)f(0)=2f(0)=2
  19. Q9 (iii)f(−1⋅5)=−2⋅5f(-1\cdot 5)=-2\cdot 5
  20. Q9 (iv)f(2)+f(−2)=1f(2)+f(-2)=1
  21. Q10 (i)f(−3)+f(2)=2f(-3)+f(2)=2
  22. Q10 (ii)f(7)−f(1)=10f(7)-f(1)=10
  23. Q10 (iii)2f(4)+f(8)=1782f(4)+f(8)=178
  24. Q10 (iv)2f(−2)−f(6)f(4)+f(−2)=−917\dfrac{2f(-2)-f(6)}{f(4)+f(-2)}=\dfrac{-9}{17}
  25. Q12 (i)t(0)=32t(0)=32
  26. Q12 (ii)t(28)=82⋅4t(28)=82\cdot 4
  27. Q12 (iii)t(−10)=14t(-10)=14
  28. Q12 (iv)C=100C=100
  29. Q12 (v)C=−40C=-40 (i.e. −40∘C=−40∘F-40^\circ\text{C}=-40^\circ\text{F})

Q1. Determine whether the graph given below represent functions. Give reason for your …

Determine whether the graph given below represent functions. Give reason for your answers concerning each graph.

(i)

Graph (i): a magenta sideways parabola opening to the left, symmetric about the X-axis with vertex just right of the origin O, on axes X'X and Y'Y.
  1. Draw a vertical line on the curve.

  2. The curve opens to the left, so a vertical line cuts it at two points.

  3. A vertical line must meet the graph at only one point for a function.

Answer

Not a function (fails the vertical line test — a vertical line meets the curve at two points).

(ii)

Graph (ii): a magenta S-shaped increasing cubic-like curve through the origin O, descending into the third quadrant and rising into the first quadrant, with arrowheads at both ends.
  1. Draw vertical lines anywhere on the curve.

  2. Each vertical line meets the S‑shaped curve at exactly one point.

  3. So every xx has only one image.

Answer

It is a function (passes the vertical line test).

(iii)

Graph (iii): a magenta S-shaped curve turned vertically about the Y-axis that doubles back on itself, so some vertical lines cut it more than once.
  1. The curve bends back on itself.

  2. A vertical line drawn in that region meets the curve at more than one point.

  3. So one xx has more than one image.

Answer

Not a function (fails the vertical line test).

(iv)

Graph (iv): a straight magenta line with arrowheads at both ends passing through the origin with positive slope, from the third quadrant to the first quadrant.
  1. The graph is a straight line through the origin.

  2. Every vertical line meets it at exactly one point.

Answer

It is a function (passes the vertical line test).

Q2. Let f:A→Bf : A \to B be a function defined by f(x)=x2−1f(x) = \dfrac{x}{2} - 1 , where A={2,4,6,10,12}A = \{2, 4, 6, 10, 12\} …

Let f:A→Bf : A \to B be a function defined by f(x)=x2−1f(x) = \dfrac{x}{2} - 1, where A={2,4,6,10,12}A = \{2, 4, 6, 10, 12\}, B={0,1,2,4,5,9}B = \{0, 1, 2, 4, 5, 9\}. Represent ff by

(i)

set of ordered pairs

Show steps (6)
  1. f(x)=x2−1f(x)=\dfrac{x}{2}-1

  2. f(2)=22−1=0f(2)=\dfrac{2}{2}-1=0

  3. f(4)=42−1=1f(4)=\dfrac{4}{2}-1=1

  4. f(6)=62−1=2f(6)=\dfrac{6}{2}-1=2

  5. f(10)=102−1=4f(10)=\dfrac{10}{2}-1=4

  6. f(12)=122−1=5f(12)=\dfrac{12}{2}-1=5

Answer

f={(2,0),(4,1),(6,2),(10,4),(12,5)}f=\{(2,0),(4,1),(6,2),(10,4),(12,5)\}

(ii)

a table

  1. Use the images found from f(x)=x2−1f(x)=\dfrac{x}{2}-1.

  2. Write xx in the first row and f(x)f(x) in the second row.

  3. x2461012f(x)01245\begin{array}{|c|c|c|c|c|c|}\hline x & 2 & 4 & 6 & 10 & 12\\\hline f(x) & 0 & 1 & 2 & 4 & 5\\\hline\end{array}

Answer

x2461012f(x)01245\begin{array}{|c|c|c|c|c|c|}\hline x & 2 & 4 & 6 & 10 & 12\\\hline f(x) & 0 & 1 & 2 & 4 & 5\\\hline\end{array}

(iii)

an arrow diagram

  1. Draw two closed curves: A={2,4,6,10,12}A=\{2,4,6,10,12\} on the left, B={0,1,2,4,5,9}B=\{0,1,2,4,5,9\} on the right.

  2. Join by arrows: 2→02\to 0, 4→14\to 1, 6→26\to 2, 10→410\to 4, 12→512\to 5.

  3. The element 99 in BB receives no arrow.

Answer

Arrow diagram: 2→0,  4→1,  6→2,  10→4,  12→52\to 0,\; 4\to 1,\; 6\to 2,\; 10\to 4,\; 12\to 5 (the element 9∈B9\in B has no pre-image).

(iv)

a graph

  1. Take the ordered pairs of ff as points.

  2. Plot (2,0),(4,1),(6,2),(10,4),(12,5)(2,0),(4,1),(6,2),(10,4),(12,5) on the graph sheet.

  3. All the points lie on a straight line (the line y=x2−1y=\dfrac{x}{2}-1).

Answer

Plot the points (2,0),(4,1),(6,2),(10,4),(12,5)(2,0),(4,1),(6,2),(10,4),(12,5); they lie on a straight line.

Q3. Represent the function f={(1,2),(2,2),(3,2),(4,3),(5,4)}f = \{(1,2),(2,2),(3,2),(4,3),(5,4)\} through

(i)

an arrow diagram

  1. Domain ={1,2,3,4,5}=\{1,2,3,4,5\}, co-domain ={2,3,4}=\{2,3,4\}.

  2. Draw arrows: 1→21\to 2, 2→22\to 2, 3→23\to 2, 4→34\to 3, 5→45\to 4.

Answer

Arrow diagram: 1→2,  2→2,  3→2,  4→3,  5→41\to2,\;2\to2,\;3\to2,\;4\to3,\;5\to4.

(ii)

a table form

  1. Write the first co-ordinates as xx and the second as f(x)f(x).

  2. x12345f(x)22234\begin{array}{|c|c|c|c|c|c|}\hline x & 1 & 2 & 3 & 4 & 5\\\hline f(x) & 2 & 2 & 2 & 3 & 4\\\hline\end{array}

Answer

x12345f(x)22234\begin{array}{|c|c|c|c|c|c|}\hline x & 1 & 2 & 3 & 4 & 5\\\hline f(x) & 2 & 2 & 2 & 3 & 4\\\hline\end{array}

(iii)

a graph

  1. Take each ordered pair as a point.

  2. Plot (1,2),(2,2),(3,2),(4,3),(5,4)(1,2),(2,2),(3,2),(4,3),(5,4) on the graph sheet.

Answer

Plot the points (1,2),(2,2),(3,2),(4,3),(5,4)(1,2),(2,2),(3,2),(4,3),(5,4).

Q4. Show that the function f:N→Nf : \mathbb{N} \to \mathbb{N} defined by f(x)=2x−1f(x) = 2x - 1 is one-one but not …

Show that the function f:N→Nf : \mathbb{N} \to \mathbb{N} defined by f(x)=2x−1f(x) = 2x - 1 is one-one but not onto.

Show steps (8)
  1. One-one: Let f(x1)=f(x2)f(x_1)=f(x_2) for x1,x2∈Nx_1,x_2\in\mathbb{N}.

  2. 2x1−1=2x2−12x_1-1=2x_2-1

  3. 2x1=2x2⇒x1=x22x_1=2x_2 \Rightarrow x_1=x_2

  4. So different elements have different images, hence ff is one-one.

  5. Onto: f(1)=1,  f(2)=3,  f(3)=5,…f(1)=1,\; f(2)=3,\; f(3)=5,\dots

  6. Range of f={1,3,5,7,… }f=\{1,3,5,7,\dots\}, the set of odd natural numbers.

  7. This is a proper subset of the co-domain N\mathbb{N} (e.g. 22 has no pre-image, since 2x−1=22x-1=2 gives x=32∉Nx=\frac32\notin\mathbb{N}).

  8. Hence ff is not onto.

Answer

ff is one-one but not onto (it is an into function).

Q5. Show that the function f:N→Nf : \mathbb{N} \to \mathbb{N} defined by f(m)=m2+m+3f(m) = m^2 + m + 3 is one-one function.

Show steps (7)
  1. Let f(m1)=f(m2)f(m_1)=f(m_2) for m1,m2∈Nm_1,m_2\in\mathbb{N}.

  2. m12+m1+3=m22+m2+3m_1^2+m_1+3=m_2^2+m_2+3

  3. m12−m22+m1−m2=0m_1^2-m_2^2+m_1-m_2=0

  4. (m1−m2)(m1+m2)+(m1−m2)=0(m_1-m_2)(m_1+m_2)+(m_1-m_2)=0

  5. (m1−m2)(m1+m2+1)=0(m_1-m_2)(m_1+m_2+1)=0

  6. Since m1,m2∈Nm_1,m_2\in\mathbb{N}, m1+m2+1≠0m_1+m_2+1\neq 0.

  7. Therefore m1−m2=0m_1-m_2=0, that is m1=m2m_1=m_2.

Answer

f(m1)=f(m2)⇒m1=m2f(m_1)=f(m_2)\Rightarrow m_1=m_2, hence ff is a one-one function.

Q6. Let A={1,2,3,4}A = \{1,2,3,4\} and B=NB = \mathbb{N} . Let f:A→Bf : A \to B be defined by f(x)=x3f(x) = x^3 then,

Let A={1,2,3,4}A = \{1,2,3,4\} and B=NB = \mathbb{N}. Let f:A→Bf : A \to B be defined by f(x)=x3f(x) = x^3 then,

(i)

find the range of ff

  1. f(x)=x3f(x)=x^3, A={1,2,3,4}A=\{1,2,3,4\}

  2. f(1)=13=1f(1)=1^3=1

  3. f(2)=23=8f(2)=2^3=8

  4. f(3)=33=27f(3)=3^3=27

  5. f(4)=43=64f(4)=4^3=64

Answer

Range of f={1,8,27,64}f=\{1,8,27,64\}

(ii)

identify the type of function

  1. Different elements of AA have different images, so ff is one-one.

  2. Co-domain =N=\mathbb{N}, but range ={1,8,27,64}=\{1,8,27,64\} is a proper subset of N\mathbb{N}.

  3. So ff is not onto; it is into.

Answer

ff is a one-one and into function.

Q7. In each of the following cases state whether the function is bijective …

In each of the following cases state whether the function is bijective or not. Justify your answer.

(i)

f:R→Rf : \mathbb{R} \to \mathbb{R} defined by f(x)=2x+1f(x) = 2x + 1

  1. One-one: f(x1)=f(x2)⇒2x1+1=2x2+1⇒x1=x2f(x_1)=f(x_2)\Rightarrow 2x_1+1=2x_2+1\Rightarrow x_1=x_2.

  2. Onto: For any y∈Ry\in\mathbb{R}, take x=y−12∈Rx=\dfrac{y-1}{2}\in\mathbb{R}; then f(x)=yf(x)=y.

  3. So every element of the co-domain has a pre-image; range =R=\mathbb{R}.

Answer

ff is bijective (one-one and onto).

(ii)

f:R→Rf : \mathbb{R} \to \mathbb{R} defined by f(x)=3−4x2f(x) = 3 - 4x^2

  1. f(1)=3−4(1)2=−1f(1)=3-4(1)^2=-1 and f(−1)=3−4(−1)2=−1f(-1)=3-4(-1)^2=-1.

  2. Two different elements 11 and −1-1 have the same image, so ff is not one-one.

  3. Also 4x2≥04x^2\ge 0, so f(x)=3−4x2≤3f(x)=3-4x^2\le 3.

  4. Range =(−∞,3]=(-\infty,3], a proper subset of R\mathbb{R}; so ff is not onto.

Answer

ff is not bijective (it is neither one-one nor onto).

Q8. Let A={−1,1}A = \{-1, 1\} and B={0,2}B = \{0, 2\} . If the function f:A→Bf : A \to B defined by f(x)=ax+bf(x) = ax + b …

Let A={−1,1}A = \{-1, 1\} and B={0,2}B = \{0, 2\}. If the function f:A→Bf : A \to B defined by f(x)=ax+bf(x) = ax + b is an onto function? Find aa and bb.

Show steps (9)
  1. f(x)=ax+bf(x)=ax+b with A={−1,1}A=\{-1,1\}, B={0,2}B=\{0,2\}.

  2. Since ff is onto, the images f(−1)f(-1) and f(1)f(1) must together cover all of B={0,2}B=\{0,2\}, so two cases arise.

  3. Case 1: f(−1)=0f(-1)=0 and f(1)=2f(1)=2.

  4. −a+b=0-a+b=0 … (1) and a+b=2a+b=2 … (2).

  5. Adding (1) and (2): 2b=2⇒b=12b=2\Rightarrow b=1; then from (2), a=1a=1.

  6. Case 2: f(−1)=2f(-1)=2 and f(1)=0f(1)=0.

  7. −a+b=2-a+b=2 … (3) and a+b=0a+b=0 … (4).

  8. Adding (3) and (4): 2b=2⇒b=12b=2\Rightarrow b=1; then from (4), a=−1a=-1.

  9. Hence a=1, b=1a=1,\,b=1 or a=−1, b=1a=-1,\,b=1; in both cases ff is onto.

Answer

a=1a=1 or a=−1a=-1, and b=1b=1

Q9. If the function ff is defined by f(x)={x+2;x>12;−1≤x≤1x−1;−3<x<−1f(x) = \begin{cases} x + 2; & x > 1 \\ 2; & -1 \le x \le 1 \\ x - 1; & -3 < x < -1 \end{cases} find the values of

(i)

f(3)f(3)

  1. x=3>1x=3>1, so use f(x)=x+2f(x)=x+2.

  2. f(3)=3+2=5f(3)=3+2=5

Answer

f(3)=5f(3)=5

(ii)

f(0)f(0)

  1. x=0x=0 lies in −1≤x≤1-1\le x\le 1, so f(x)=2f(x)=2.

  2. f(0)=2f(0)=2

Answer

f(0)=2f(0)=2

(iii)

f(−1⋅5)f(-1\cdot 5)

  1. x=−1⋅5x=-1\cdot5 lies in −3<x<−1-3<x<-1, so f(x)=x−1f(x)=x-1.

  2. f(−1⋅5)=−1⋅5−1=−2⋅5f(-1\cdot5)=-1\cdot5-1=-2\cdot5

Answer

f(−1⋅5)=−2⋅5f(-1\cdot 5)=-2\cdot 5

(iv)

f(2)+f(−2)f(2) + f(-2)

  1. x=2>1x=2>1, so f(2)=2+2=4f(2)=2+2=4.

  2. x=−2x=-2 lies in −3<x<−1-3<x<-1, so f(−2)=−2−1=−3f(-2)=-2-1=-3.

  3. f(2)+f(−2)=4+(−3)=1f(2)+f(-2)=4+(-3)=1

Answer

f(2)+f(−2)=1f(2)+f(-2)=1

Q10. A function f:[−5,9]→Rf : [-5, 9] \to \mathbb{R} is defined as follows: $$f(x) = \begin{cases} 6x + …

A function f:[−5,9]→Rf : [-5, 9] \to \mathbb{R} is defined as follows: f(x)={6x+1;−5≤x<25x2−1;2≤x<63x−4;6≤x≤9f(x) = \begin{cases} 6x + 1; & -5 \le x < 2 \\ 5x^2 - 1; & 2 \le x < 6 \\ 3x - 4; & 6 \le x \le 9 \end{cases} Find

(i)

f(−3)+f(2)f(-3) + f(2)

  1. −3-3 lies in −5≤x<2-5\le x<2, so f(−3)=6(−3)+1=−17f(-3)=6(-3)+1=-17.

  2. 22 lies in 2≤x<62\le x<6, so f(2)=5(2)2−1=19f(2)=5(2)^2-1=19.

  3. f(−3)+f(2)=−17+19=2f(-3)+f(2)=-17+19=2

Answer

f(−3)+f(2)=2f(-3)+f(2)=2

(ii)

f(7)−f(1)f(7) - f(1)

  1. 77 lies in 6≤x≤96\le x\le 9, so f(7)=3(7)−4=17f(7)=3(7)-4=17.

  2. 11 lies in −5≤x<2-5\le x<2, so f(1)=6(1)+1=7f(1)=6(1)+1=7.

  3. f(7)−f(1)=17−7=10f(7)-f(1)=17-7=10

Answer

f(7)−f(1)=10f(7)-f(1)=10

(iii)

2f(4)+f(8)2f(4) + f(8)

  1. 44 lies in 2≤x<62\le x<6, so f(4)=5(4)2−1=79f(4)=5(4)^2-1=79.

  2. 88 lies in 6≤x≤96\le x\le 9, so f(8)=3(8)−4=20f(8)=3(8)-4=20.

  3. 2f(4)+f(8)=2(79)+20=158+20=1782f(4)+f(8)=2(79)+20=158+20=178

Answer

2f(4)+f(8)=1782f(4)+f(8)=178

(iv)

2f(−2)−f(6)f(4)+f(−2)\dfrac{2f(-2) - f(6)}{f(4) + f(-2)}

  1. −2-2 lies in −5≤x<2-5\le x<2, so f(−2)=6(−2)+1=−11f(-2)=6(-2)+1=-11.

  2. 66 lies in 6≤x≤96\le x\le 9, so f(6)=3(6)−4=14f(6)=3(6)-4=14.

  3. 44 lies in 2≤x<62\le x<6, so f(4)=5(4)2−1=79f(4)=5(4)^2-1=79.

  4. 2f(−2)−f(6)f(4)+f(−2)=2(−11)−1479+(−11)\dfrac{2f(-2)-f(6)}{f(4)+f(-2)}=\dfrac{2(-11)-14}{79+(-11)}

  5. =−22−1468=−3668=−917=\dfrac{-22-14}{68}=\dfrac{-36}{68}=\dfrac{-9}{17}

Answer

2f(−2)−f(6)f(4)+f(−2)=−917\dfrac{2f(-2)-f(6)}{f(4)+f(-2)}=\dfrac{-9}{17}

Q11. The distance SS an object travels under the influence of gravity in …

The distance SS an object travels under the influence of gravity in time tt seconds is given by S(t)=12gt2+at+bS(t) = \dfrac{1}{2}gt^2 + at + b where, (gg is the acceleration due to gravity), a>0a > 0, bb are constants. Verify wheather the function S(t)S(t) is one-one or not.

Show steps (6)
  1. Assume S(t1)=S(t2)S(t_1)=S(t_2).

  2. 12gt12+at1+b=12gt22+at2+b\dfrac12 gt_1^2+at_1+b=\dfrac12 gt_2^2+at_2+b

  3. 12g (t12−t22)+a(t1−t2)=0\dfrac12 g\,(t_1^2-t_2^2)+a(t_1-t_2)=0

  4. (t1−t2)[g2(t1+t2)+a]=0(t_1-t_2)\left[\dfrac{g}{2}(t_1+t_2)+a\right]=0

  5. Time t1,t2≥0t_1,t_2\ge 0 and g>0,  a>0g>0,\;a>0, so g2(t1+t2)+a>0\dfrac{g}{2}(t_1+t_2)+a>0.

  6. Hence t1−t2=0t_1-t_2=0, that is t1=t2t_1=t_2.

Answer

S(t1)=S(t2)⇒t1=t2S(t_1)=S(t_2)\Rightarrow t_1=t_2, so S(t)S(t) is a one-one function.

Q12. The function 'tt' which maps temperature in Celsius (CC) into temperature in …

The function 'tt' which maps temperature in Celsius (CC) into temperature in Fahrenheit (FF) is defined by t(C)=Ft(C) = F where F=95C+32F = \dfrac{9}{5}C + 32. Find,

(i)

t(0)t(0)

  1. F=95C+32F=\dfrac95 C+32

  2. t(0)=95(0)+32=32t(0)=\dfrac95(0)+32=32

Answer

t(0)=32t(0)=32

(ii)

t(28)t(28)

  1. t(28)=95(28)+32t(28)=\dfrac95(28)+32

  2. =2525+32=50⋅4+32=\dfrac{252}{5}+32=50\cdot4+32

  3. =82⋅4=82\cdot4

Answer

t(28)=82⋅4t(28)=82\cdot 4

(iii)

t(−10)t(-10)

  1. t(−10)=95(−10)+32t(-10)=\dfrac95(-10)+32

  2. =−18+32=14=-18+32=14

Answer

t(−10)=14t(-10)=14

(iv)

the value of CC when t(C)=212t(C) = 212

  1. t(C)=212⇒95C+32=212t(C)=212\Rightarrow \dfrac95 C+32=212

  2. 95C=180\dfrac95 C=180

  3. C=180×59=100C=180\times\dfrac59=100

Answer

C=100C=100

(v)

the temperature when the Celsius value is equal to the Farenheit value.

  1. Let F=CF=C.

  2. C=95C+32C=\dfrac95 C+32

  3. 5C=9C+1605C=9C+160

  4. −4C=160-4C=160

  5. C=−40C=-40

Answer

C=−40C=-40 (i.e. −40∘C=−40∘F-40^\circ\text{C}=-40^\circ\text{F})

Quick check

  1. Let ff and gg be two functions given by f={(0,1),(2,0),(3,−4),(4,2),(5,7)}f = \{(0,1),(2,0),(3,-4),(4,2),(5,7)\}, g={(0,2),(1,0),(2,4),(−4,2),(7,0)}g = \{(0,2),(1,0),(2,4),(-4,2),(7,0)\} then the range of f∘gf \circ g is

    1. (1) {0,2,3,4,5}\{0,2,3,4,5\}
    2. (2) {−4,1,0,2,7}\{-4,1,0,2,7\}
    3. (3) {1,2,3,4,5}\{1,2,3,4,5\}
    4. (4) {0,1,2}\{0,1,2\}
    Show answer

    Answer: (4) {0,1,2}\{0,1,2\}

    1. (f∘g)(0)=f(2)=0(f\circ g)(0)=f(2)=0, (f∘g)(1)=f(0)=1(f\circ g)(1)=f(0)=1.

    2. (f∘g)(2)=f(4)=2(f\circ g)(2)=f(4)=2, (f∘g)(−4)=f(2)=0(f\circ g)(-4)=f(2)=0, (f∘g)(7)=f(0)=1(f\circ g)(7)=f(0)=1.

    3. Range ={0,1,2}=\{0,1,2\}.

    Question 1 of 5
  2. If there are 1024 relations from a set A={1,2,3,4,5}A = \{1, 2, 3, 4, 5\} to a set BB, then the number of elements in BB is

    1. (1) 3
    2. (2) 2
    3. (3) 4
    4. (4) 8
    Show answer

    Answer: (2) 2

    1. Number of relations from AA to BB is 2n(A)⋅n(B)2^{n(A)\cdot n(B)}.

    2. 25 n(B)=1024=2102^{5\,n(B)}=1024=2^{10}.

    3. 5 n(B)=10⇒n(B)=25\,n(B)=10\Rightarrow n(B)=2.

    Question 2 of 5
  3. Let A={1,2,3,4}A = \{1,2,3,4\} and B={4,8,9,10}B = \{4,8,9,10\}. A function f:A→Bf : A \to B given by f={(1,4),(2,8),(3,9),(4,10)}f = \{(1,4),(2,8),(3,9),(4,10)\} is a

    1. (1) Many-one function
    2. (2) Identity function
    3. (3) One-to-one function
    4. (4) Into function
    Show answer

    Answer: (3) One-to-one function

    1. Images are 4,8,9,104,8,9,10 — all different.

    2. Different elements of AA have different images.

    3. So ff is one-to-one.

    Question 3 of 5
  4. If f(x)=2x2f(x) = 2x^2 and g(x)=13xg(x) = \dfrac{1}{3x}, then f∘gf \circ g is

    1. (1) 32x2\dfrac{3}{2x^2}
    2. (2) 23x2\dfrac{2}{3x^2}
    3. (3) 29x2\dfrac{2}{9x^2}
    4. (4) 16x2\dfrac{1}{6x^2}
    Show answer

    Answer: (3) 29x2\dfrac{2}{9x^2}

    1. (f∘g)(x)=f(g(x))=f(13x)(f\circ g)(x)=f\big(g(x)\big)=f\left(\dfrac{1}{3x}\right).

    2. =2(13x)2=2\left(\dfrac{1}{3x}\right)^{2}.

    3. =29x2=\dfrac{2}{9x^{2}}.

    Question 4 of 5
  5. A={a,b,p}A = \{a,b,p\}, B={2,3}B = \{2,3\}, C={p,q,r,s}C = \{p,q,r,s\} then n[(A∪C)×B]n[(A \cup C) \times B] is

    1. (1) 8
    2. (2) 20
    3. (3) 12
    4. (4) 16
    Show answer

    Answer: (3) 12

    1. A∪C={a,b,p,q,r,s}A\cup C=\{a,b,p,q,r,s\}, so n(A∪C)=6n(A\cup C)=6.

    2. n(B)=2n(B)=2.

    3. n[(A∪C)×B]=6×2=12n[(A\cup C)\times B]=6\times 2=12.

    Question 5 of 5
Chapter 1 formulas
  • Cartesian product of A with B

    A×B={(a,b)∣for all a∈A, b∈B}A \times B = \{(a,b) \mid \text{for all } a \in A,\ b \in B\}

  • A relation R from A to B is a subset of A × B

    R⊆A×BR \subseteq A \times B

  • Condition for a relation R from X to Y to be a function

    for every x∈X there exists only one y∈Y\text{for every } x \in X \text{ there exists only one } y \in Y

  • Identity function

    f(x)=xf(x) = x

  • Reciprocal function

    f(x)=1xf(x) = \dfrac{1}{x}

  • Constant function

    f(x)=cf(x) = c

  • Linear function

    f(x)=ax+b, a≠0f(x) = ax + b,\ a \neq 0

  • Quadratic function

    f(x)=ax2+bx+c, a≠0f(x) = ax^{2} + bx + c,\ a \neq 0

  • Cubic function

    f(x)=ax3+bx2+cx+d, a≠0f(x) = ax^{3} + bx^{2} + cx + d,\ a \neq 0

  • Composition of two functions f : A → B and g : B → C

    g∘f:A→C,(g∘f)(x)=g(f(x))  for all x∈Ag \circ f : A \to C,\quad (g \circ f)(x) = g(f(x)) \ \text{ for all } x \in A

  • Composition is not commutative in general

    f∘g≠g∘ff \circ g \neq g \circ f

  • Composition is associative

    f∘(g∘h)=(f∘g)∘hf \circ (g \circ h) = (f \circ g) \circ h

Answers checked against the Samacheer Kalvi textbook · Updated

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