Add and .

Apply the distributive property.

Rewrite using the commutative property of multiplication.

Raise to the power of .

Use the power rule to combine exponents.

Move .

Multiply by .

Raise to the power of .

Use the power rule to combine exponents.

Combine the opposite terms in .

Add and .

Add and .

Simplify t(t^(n-1)+t^n+t^(n-1))