For any product in form (a+b+c)*(d+e), we solve if multiplying each term from (a+b+c) by each term from (d+e) as follows:
(a+b+c)*(d+e) = ad + bd + cd + ae + be + ce
Aplying that rule on the product (2x^2 + 5x + 3)*(4x - 8), we have
(2x^2 + 5x + 3)*(4x - 8) = (4x)*(2x^2) + (4x)*(5x) + (4x)*(3) + (-8)*(2x^2) + (-8)*(5x) + (-8)*(3) = 8x^3 + 20x^2 + 12x - 16x^2 - 40x - 24 = 8x^3 + 4x^2 - 28x - 24
(2x^2 + 5x + 3)*(4x - 8) = 8x^3 + 4x^2 - 28x - 24
