Find the inflection points of (f)x= 9 sin x + cos x

inflection-points

#1

find the inflection points of (f)x= 9 sin x + cos x

Answer:

inflection points occur where f’’(x)=0
f’(x)=9 cos x- sin x
f’’(x)= -9 sinx - cos x
putting f’’(x)=0
we get: 9 sin x=- cos x
i.e. tan x=-(1/9)
So tan inverse(-1/9) is the inflection point