,

Set up the composite result function.

Evaluate by substituting in the value of into .

Rewrite as .

Expand using the FOIL Method.

Apply the distributive property.

Apply the distributive property.

Apply the distributive property.

Simplify and combine like terms.

Simplify each term.

Multiply by by adding the exponents.

Use the power rule to combine exponents.

Add and .

Move to the left of .

Multiply by .

Add and .

Subtract from .

Find g(f(x)) f(x)=x^2+8 , g(x)=x^2-8