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Relations And Functions

Question
CBSEENMA12035774

Differentiate the function (sin x)x + sin–1 √xwith respect to x.

Solution
straight y space equals space left parenthesis sin space straight x right parenthesis to the power of straight x space plus sin to the power of negative 1 end exponent space square root of straight x
straight y space equals space straight u plus straight v
rightwards double arrow space dy over dx space equals space du over dx space plus dv over dx
straight u space equals space left parenthesis sin space straight x right parenthesis to the power of straight x
rightwards double arrow space log space straight u space equals space straight x space log space sin space straight x
rightwards double arrow du over dx space equals space left parenthesis sin space straight x right parenthesis to the power of straight x left square bracket space straight x space cot space straight x space plus space log space sin space straight x right square bracket

straight v equals space sin to the power of negative 1 end exponent square root of straight x space
rightwards double arrow space dv over dx space equals space fraction numerator 1 over denominator 2 square root of straight x minus straight x squared end root end fraction
therefore dy over dx space equals space left parenthesis sin space straight x right parenthesis to the power of straight x space left square bracket straight x space cot space straight x space plus space log space sin space straight x right square bracket space plus fraction numerator 1 over denominator 2 square root of straight x minus straight x squared end root end fraction

Some More Questions From Relations and Functions Chapter

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.

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