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Relations And Functions

Question
CBSEENMA12036216

Let f : (-1, 1) → B, be a function defined by straight f left parenthesis straight x right parenthesis space equals space tan to the power of negative 1 end exponent space fraction numerator 2 straight x over denominator 1 minus straight x squared end fraction comma space then f is both one-one and onto when B is the interval

  • open parentheses 0 comma space straight pi over 2 close parentheses
  • [0, π/2)

  • open parentheses negative straight pi over 2 comma straight pi over 2 close parentheses
  • open square brackets negative straight pi over 2 comma straight pi over 2 close square brackets

Solution

C.

open parentheses negative straight pi over 2 comma straight pi over 2 close parentheses Given space straight f left parenthesis straight x right parenthesis space equals space tan to the power of negative 1 end exponent space open parentheses fraction numerator 2 straight x over denominator 1 minus straight x squared end fraction close parentheses space for space straight x element of space left parenthesis negative 1 comma 1 right parenthesis
Clearly space range space of space straight f left parenthesis straight x right parenthesis space equals open parentheses negative straight pi over 2 comma straight pi over 2 close parentheses
therefore space co minus domain space of space function space equals space straight B space equals space open parentheses negative straight pi over 2 comma straight pi over 2 close parentheses

Some More Questions From Relations and Functions Chapter

Show that the relation R in the set {1, 2, 3} given by R = {(1, 1), (2, 2), (3, 3), (1, 2), (2, 3)} is reflexive but neither symmetric nor transitive.

Show that the relation R in the set {1, 2, 3} given by R = {(1, 2), (2, 1)} is symmetric but neither reflexive nor transitive.

Give an example of a relation which is

(i) Symmetric but neither reflexive nor transitive.
(ii) Transitive but neither reflexive nor symmetric.
(iii) Reflexive and symmetric but not transitive.
(iv) Reflexive and transitive but not symmetric.
(v) Symmetric and transitive but not reflexive.

Let L be the set of all lines in a plane and R be the relation in L defined as R = {(L1, L2) : L1 is perpendicular to L2}. Show that R is symmetric but neither reflexive nor transitive.

 Determine whether each of the following relations are reflexive, symmetric and transitive :

(i) Relation R in the set A = {1, 2, 3,....., 13, 14} defined as

R = {(x, y) : 3 x – y = 0}

(ii) Relation R in the set N of natural numbers defined as R = {(x, y) : y = x + 5 and x < 4} (iii) Relation R in the set A = {1, 2, 3, 4, 5, 6} as R = {(x,y) : y is divisible by x} (iv) Relation R in the set Z of all integers defined as R = {(x,y) : x – y is an integer}

(v) Relation R in the set A of human beings in a town at a particular time given by
(a)    R = {(x, y) : x and y work at the same place}
(b)    R = {(x,y) : x and y live in the same locality}
(c)    R = {(x, y) : x is exactly 7 cm taller than y}
(d)    R = {(x, y) : x is wife of y}
(e)    R = {(x,y) : x is father of y}

Check whether the relation R defined in the set {1, 2, 3, 4, 5, 6} as R = {(a, b) : b = a + 1} is reflexive, symmetric or transitive.

Show that the relation R in R defined as R = {(a, b) : a ≤ b}, is reflexive and transitive but not symmetric.

Check whether the relation R in R defined by R = {(a,b) : a ≤ b3} is refleive, symmetric or transitive.

If R and R’ arc reflexive relations on a set then so are R ∪ R’ and R ∩ R’.