Question
Mathematics Question on Derivatives
If y(x)=xx,x>0, then y′′(2)−2y′(2) is equal to :
A
4(loge2)2−2
B
8loge2−2
C
4(loge2)2+2
D
4loge2+2
Answer
4(loge2)2−2
Explanation
Solution
y′=xx
y′=xx(1+ℓnx)
y′′=xx(1+ℓnx)2+xx⋅x1
y′′(2)=4(1+ℓn2)2+2
y′(2)=4(1+ℓn2)
y′′(2)−2y′(2)=4(1+ℓn2)2+2−8(1+ℓn2)
=4(1+ℓn2)[1+ℓn2−2]+2
=4(ℓn2)2−1)+2
=4(ℓn2)2−2