Question

1). (fog)(x) = x^2+3x+1
g(x) = x+1
f(x) = ?

2). (gof)(x) = 2x^2+8x-11
g(x) = 2x+1
f(x) = ?

Answer 1

Fog(x)=f o g
fog(x)=f(x+1)
x²+3x+1=f(x+1)
f(x+1) =x²+3x+1
f(x+1)=(x+1)²+ (x+1) -1     
f(a) = a²+a-1
f(x) = x²+a-1