# How do you simplify #5/ ( x + 8) + 8/ ( x - 9) = 4/( x ^ { 2} - x - 72)#?

##### 1 Answer

Sep 19, 2017

factor the denominator of the RHS first.

note that the factors appear in both denominators of the LHS.

Eliminate the fractions by multiplying both sides by the LCD (lowest common denominator) and you're on your way.

#### Explanation:

multiplying both sides by the LCD of (x+8)(x-9), we would have

5(x-9) + 8(x+8) = 4

Note that the factors of the denominator on the RHS are the LCD and will cancel out.

expanding,

5x - 45 + 8x + 64 = 4

combining terms

13x + 19 = 4

13x = -15

x = -15/13