(4)
y'=x
y= (1/2)x^2 +C
y(0) =1 => C=1
ie
y= (1/2)x^2 +1
ans : C
(5)
f(x) =x^3
f(-x) = -f(x)
=>
∫(-1->1) x^3 dx =0
ans : D
(6)
∫(-a->a) dx
=2a
