Expert: Scott A Wilson - 3/22/2011

Question
(y+3)/(y^2-2y-3)-(7)/(y^2-1) how do i preform indicaated operation for this

Answer
To perform the subtraction, the two fractions need a common denominator.

The 1st fraction has (y-3)(y+1) in the denominator and
the 2nd fraction has (y-1)(y+1) in the denominator.

To combine them, multiply the 1st fraction by (y-1)/(y-1) and the 2nd fraction by (y-3)/(y-3).
This gives [(y+3)(y-1) - 7(y-3)]/[(y+1)(y-3)(y-1)].
Multiplying the numerator out gives (y² + 2y - 3 - 7y + 21).
Combining like terms gives (y² - 5y + 18) in the numerator.

Putting that back over the common denominator that was found gives
(y² - 5y + 1)/[(y+1)(y-3)(y-1)].  The top does not factor.
The bottom is OK as stands or it might suppose to be the answer multipled out.