Question

Let `f(x)-4x +5 and g(x)= -4x^2 -5`. What is `(f*g) (-1)`?

Answer 1

I used `(f.g) (-1)=f[g(-1)]` identity,

`g(-1)=-4*(-1)^2-5=-9`

Hence, `(f.g) (-1)=f[g(-1)]=f(-9)=(-4)*(-9)+5=41`

Explanation:

1) I found `g(-1)`.

2) I wrote value of `g(-1)` in place of `x` for finding `(f.g) (-1)`