Question

F(x)=-2x-1 and g(x)=x^2-1. Find (fog)(-5).

Answer 1

Answer: - 49

Explanation:

f(x) = -2x - 1

g(x) =
`x^(2)` - 1

fg(x) = f (
`x^(2)` - 1) , we just put in the value of g(x) , the next thing is to substitute
`x^(2)` - 1 for the value of x in f(x) , that is

fg(x) = -2(
`x^(2)` - 1) - 1

fg(x) = -2
`x^(2)` + 2 - 1

fg(x) = -2
`x^(2)` + 1

Therefore : fg(-5) means we will substitute -5 for x in fg(x) , that is

fg(-5) = -2 (
`(-5)^(2)` + 1

fg(-5) = -2(25) + 1

fg(-5) = -50 + 1

fg(-5) = -49