Find the Lcd of the rational expression. Also find the differnce of the rational expression in the simplest form.

7/y,21/x^2-y

Guest Feb 25, 2017

#1**0 **

Find:

(1) \(\text{LCD of }\dfrac{7}{y}\text{ and }\dfrac{21}{x^2-y}\)

and

(2) \(\dfrac{7}{y}-\dfrac{21}{x^2-y}\)

First question:

\(\text{LCD}(\dfrac{7}{y},\dfrac{21}{x^2-y})\\ =\text{LCM}(y,x^2-y)\\ =x^2y-y^2\)

Second question:

\(\dfrac{7}{y}-\dfrac{21}{x^2-y}\\ =\dfrac{7(x^2-y)}{x^2y-y^2}-\dfrac{21y}{x^2y-y^2}\\ =\dfrac{7x^2-7y-21y}{x^2y-y^2}\\ =\dfrac{7x^2-28y}{x^2y-y^2}\)

MaxWong
Feb 25, 2017