Question

Find the least common denominator for these two rational expressions.

y/y^2 -1                 y/y^2 -8y+7

Answer 1

`(y)/(y^(2)-1),\ (y)/(y^(2)-8y+7)`

`=(y)/((y-1)(y+1)),\ (y)/((y-1)(y-7))`

`=(y(y-7))/((y-1)(y+1)(y-7)),\ (y(y+1))/((y-1)(y+1)(y-7))`

So the common denominator is
`(y-1)(y+1)(y-7)`