How do you multiply (x^2-x-6)/(x^2+4x+3) *( x^2-x-12)/(x^2-2x-8)x2x6x2+4x+3x2x12x22x8?

1 Answer
Apr 5, 2016

(x^2-x-6)/(x^2+4x+3)*(x^2-x-12)/(x^2-x-8)=(x-3)/(x+1)x2x6x2+4x+3x2x12x2x8=x3x+1

Explanation:

To solve the multiplication, we should first factorize each quadratic polynomial. Hence,

x^2-x-6=x^2-3x+2x-6=x(x-3)+2(x-3)=(x+2)(x-3)x2x6=x23x+2x6=x(x3)+2(x3)=(x+2)(x3)

x^2+4x+3=x^2+3x+x+3=x(x+3)+1(x+3)=(x+1)(x+3)x2+4x+3=x2+3x+x+3=x(x+3)+1(x+3)=(x+1)(x+3)

x^2-x-12=x^2-4x+3x-12=x(x-4)+3(x-4)=(x+3)(x-4)x2x12=x24x+3x12=x(x4)+3(x4)=(x+3)(x4)

x^2-x-8=x^2-4x+2x-8=x(x-4)+2(x-4)=(x+2)(x-4)x2x8=x24x+2x8=x(x4)+2(x4)=(x+2)(x4)

Hence (x^2-x-6)/(x^2+4x+3)*(x^2-x-12)/(x^2-x-8)x2x6x2+4x+3x2x12x2x8

= ((x+2)(x-3))/((x+1)(x+3))*((x+3)(x-4))/((x+2)(x-4))(x+2)(x3)(x+1)(x+3)(x+3)(x4)(x+2)(x4)

= ((cancel(x+2))(x-3))/((x+1)(cancel(x+3)))*((cancel(x+3))(cancel(x-4)))/(cancel((x+2))(cancel(x-4)))

=(x-3)/(x+1)