Q.

Let f : RR be a twice differentiable function such that f(2) = 1. If F(x) = xf(x) for all xR02xF'(x)dx=6 and 02x2F''(x)dx=40, then F'(2)+02F(x)dx is equal to :          [2025]

1 13  
2 9  
3 11  
4 15  

Ans.

(3)

We have, 02xF'(x)dx=6          ... (i)

 [xF(x)]0202F(x)dx=6

 2F(2)02F(x)dx=6

 402F(x)dx=6           [ F(2)=2f(2)=2]

 02F(x)dx=2

Also,  02x2F''(x)dx=40

 [x2F'(x)]02202xF'(x)dx=40

 4F'(2)2(6)=40  F'(2)=13          [Using (i)]

Thus, F'(2)+02F(x)dx=132=11