Q. 205.0( 2 Votes )

Let . If f(x) is continuous at
find a and b.  (CBSE 2016)

Answer :

Given:


f(x) is continuous at x = & f() = a,


If f(x) to be continuous at x = ,we have to show, f() = f() + = f()


LHL = f() =



sin(–x) = cosx


cos(–x) = sinx





(a3–b3) = (a–b)(a2 + ab + b2)






cos(0) = 1




...(1)


LHL = f() + =











1


...(2)


f(x) is continuous at x = & f() = a ,and from (1) & (2),we get


f() = f() + = f()


= a


a =



b = 4


Hence ,a = & b = 4

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