Multiplying Polynomials: (x^2+3x-5)(x^2-x+1)

Question

Even when multiplying trinomials

Answer 1

An easy way to keep organized is to use a rectangular box. There are three terms in each polynomial so make a box that is 3 x 3 and put one polynomial on the top, one term per space, and put the second polynomial on the side, again one term per space, like this:

:

Then multiply each pair and put the answer in the space. First multiply x² and x² (giving you x4) and put it in the space below the top x² and to the right of the side x². Then repeat to fill the box. You'll get this:

The add up all the like-terms to get the answer. There is just one x⁴ term. There are two x³ terms and they add to 2x³, etc. Put all the results together to get your final answer.