\((16x^3+40x^2+72)(2x+6)=32x^4+96x^3+80x^3+240x^2+144x+432=32x^4+176x^3+240x^2+144x+432\)
In this case, you have to multiply each term of one parenthesis by each term in the second bracket. After receiving a number of factors need to be segregated and placed in the correct order.
