Help with fing the LCD

[Guest]

I need to find the Least Common Denominator for these two rational expression. I am not sure how to begin this problem.

4 5x
— * —
x-y 2y-2x


3 2b -5
____ , _____ , _____
4b^2 2b+3 2b^2-3b

Plese help me to complete this problem.

Thank you

 

[Gene]

Note that 2y-2x = -2(x-y)
You can move the minus up to -5 then the denominators are
2 and (x-y) so the LCD is 2(x-y) but you don't need that since you are multiplying.

The second has denominator parts of
4, b^2, 2b+3, 2b-3, and b
You want to find the highest powers of each part.
The b is included in b^2 so the LCD is the product of 4, b^2, 2b+3 and 2b-3