
Kemal G. answered 04/10/17
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Hi Lauren,
Please use parentheses to specify the expressions! I am assuming that the expression is (3 sqrt x - sqrt y) / (sqrt y + sqrt x)
To rationalize the denominator, multiply the expression by the conjugate of the denominator, which is equal to sqrt(y)-sqrt(x)
(3 sqrt x - sqrt y) (sqrt(y)-sqrt(x))
-------------------------------------------
(sqrt y + sqrt x) (sqrt(y)-sqrt(x)) (this is equal to the difference of two squares)
(3sqrt(xy) - 3x - y - sqrt(xy))
= ------------------------------------
y - x
-3x - y - 2sqrt(xy)
= ------------------------
y - x