Solveeit Logo
Login

Question

Question: Let f(x) = e<sup>x</sup> cos x and slope of the curve y = f(x) is maximum at x = a then a equals...

Let f(x) = ex cos x and slope of the curve y = f(x) is maximum at x = a then a equals

A

0

B

π2\frac { \pi } { 2 }

C

3π2\frac { 3 \pi } { 2 }

D

) None of these

Answer

0

Explanation

Solution

Q f ¢(x) = m = ex[cosx – sinx]

= ex (– sinx – cosx) + (cosx – sinx)ex

= –2sin xex = 0

Ž x = 0, p ..........

= – 2[ex cos x + ex sin x]

= – 2 < 0 Ž max. at x = 0