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Relations And Functions

Question
CBSEENMA12036152

Let f(x) = x|x| and g(x) = sinx

Statement 1 : gof is differentiable at x = 0 and its derivative is continuous atthat point
Statement 2: gof is twice differentiable at x = 0

  • Statement–1 is true, Statement–2 is true, Statement–2 is a correct explanation for statement–1

  • Statement–1 is true, Statement–2 is true;Statement–2 is not a correct explanation for statement–1.

  • Statement–1 is true, statement–2 is false.

  • Statement–1 is false, Statement–2 is true

Solution

C.

Statement–1 is true, statement–2 is false.

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left parenthesis straight g left parenthesis straight f left parenthesis straight x right parenthesis right parenthesis right parenthesis apostrophe space equals space open curly brackets table attributes columnalign left end attributes row cell 2 straight x space cos space straight x squared comma space space straight x greater or equal than 0 end cell row cell negative 2 straight x space cos space straight x squared comma space straight x less than 0 end cell end table close
straight R. straight H. straight D space of space left parenthesis straight g left parenthesis straight f left parenthesis 0 right parenthesis right parenthesis right parenthesis apostrophe space equals space limit as straight h rightwards arrow 0 to the power of plus of space fraction numerator 2 straight h space cos space straight h squared over denominator straight h end fraction space equals space 2
straight L. straight H. straight D space of space left parenthesis straight g space left parenthesis straight f left parenthesis 0 right parenthesis right parenthesis right parenthesis apostrophe space equals space limit as straight h rightwards arrow 0 to the power of plus of space fraction numerator 2 straight h space cosh squared over denominator negative straight h end fraction space equals space minus 2
Clearly gof is twice differentiable at x = 0 hence it is differentiable at x = 0 and its derivative is continuous at x = 0

Some More Questions From Relations and Functions Chapter

lf a matrix has 18 elements, what are the possible orders it can have ? What, if it has 5 elements?

If a matrix A has 12 elements, what arc the possible orders it can have 7 What if it has 7 elements ?

Let A be the set of all students of a boys school. Show that the relation R in A given by R = {(a, b) : a is sister of b} is the empty relation and R’ = {(a, b) : the difference between heights of a and b is less than 3 meters} is the universal relation.

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.