Expert: Steve Holleran - 10/31/2007

Question
I do not understand polynomials and am struggling to figure out how to multiply fractions with polynomials.

These are fractions

2x^2 - x - 3/3x^2 + 7x + 4 * 3x^2 - 11x - 20/4x^2 - 9

Answer
Hi Annalene,

Okay, what you want to do is to factor each numerator and denominator:

(2x-3)(x+1) /(3x+4)(x+1) * (3x+4)(x-5)/(2x+3)(2x-3)

Now cancel out all the common factors that show up on the top and bottom: the (2x-3)'s, the (3x+4)'s and the (x+1)'s.

That leaves you with:   (x-5) / (2x+3)

All multiplication of rational expressions problems are done this same way: factor, then cancel.

Hope this helps
Steve