Question 35435
I am assuming that you probably meant this fraction:
{{{(y + 5)/ (y - 5) - (2y)/ (y^2 - 25)}}}


First, factor the second denominator in order to find the LCD:
{{{(y + 5)/ (y - 5) - (2y)/ ((y - 5)*(y+5))}}}
The LCD is {{{(y-5)*(y+5)}}}


Now, in order to subtract the fractions, you must get the LCD in the first fraction, by multiplying the numerator and denominator of the first fraction by (y+5).

{{{ ((y + 5)/(y - 5))*((y+5)/(y+5)) - (2y)/ ( (y - 5)*(y+5) )  }}}


Multiply out the first numerator:
{{{ (y^2 + 10y +25)/ ((y - 5)*(y+5)) - (2y)/ ((y - 5)*(y+5))}}}


Combine the numerators:

{{{ (y^2 +8y + 15) / ((y-5)*(y+5)) }}}


R^2 at SCC