Which is the fully factored form of 32x3+28x-20?

4x(8^2+7x+5)

4(8^3+7x-5)

4x(8^3+7x-5)

4(8^2+7x-5)

The fully factored form of 32x^3+28x-20 is 4x(8^2+7x-5).