How do you evaluate \frac { 5x + 15} { x ^ { 2} + 2x - 3} \cdot \frac { 7x - 7} { 10x + 20}?

1 Answer
Oct 20, 2017

3.5/(x+2)

Explanation:

You can't evaluate for x, but you can simplify this expression using factoring and dividing away numbers:

First factor:

(5(x+3))/((x+3)(x-1))*(7(x-1))/(10(x+2))

Multiply across:

(5(x+3)7(x-1))/((x+3)(x-1)10(x+2))

Divide away equivalent factors:

(5cancel((x+3))7cancel((x-1)))/(cancel((x+3))cancel((x-1))10(x+2))

Thus we are left with:

35/(10(x+2))=3.5/(x+2)