We will have to multiply each term of the second trinomial by the first term of the first trinomial and then repeat the multiplication by multiplying each term of the second trinomial by the second term of the first trinomial and finally multiply each term of the second trinomial by the third term of the first trinomial. This can be done by either the horizontal method or the vertical method of multiplication. How to Multiply Trinomials Below see the steps on how to multiply trinomials -