# Simplify (-4x+6)/(x^2-9) – (-5x+3)/(x^2-9)?-Collection of common programming errors

i solved it and i got undefined because the bottom would be zero but the answer key says 1/x-3

so please show me how to get to that. thank you!

- How did you get the bottom to be 0? Did you subtract correctly? You have two fractions here with the same denominator, so just subtract the numerators and put this difference on top of the same denominator. [ (-4x+6) – (-5x+3) ] / (x^2 – 9) [ -4x + 6 + 5x – 3 ] / (x^2 – 9) [ x + 3 ] / (x^2 – 9) [ x + 3 ] / (x+3)(x-3)
1 / (x-3)

- (-4x+6)/(x^2-9) – (-5x+3)/(x^2-9) The 2 fractions have the same denominator, so =((-4x) + 6) – (-5x+3))/(x^2-9) Collect like terms =(-4x – -5x +6-3)/(x^2-9) = (-4x+5x + 3)/(x^2-9) =(x + 3)/(x^2-9) Now factor the denominator, which is the difference of squares = (x+3)/(x-3)(x+3)
= 1/(x-3)

Originally posted 2013-11-09 21:55:41.