Jason S. answered 11/02/13
Tutor
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(116)
My goal is the success of my students. Knowledge-Patience-Honesty
Now, this is a weird question, because the answer is more complicated to evaluate than the original question. However, it appears they want you to rationalize the denominator.
sqrt(x)
----------
3*sqrt(x) - sqrt(y)
Multiply top and bottom by the conjugate:
x1/2(3x1/2 + y1/2)
----------------------
(3x1/2 - y1/2)(3x1/2 + y1/2)
3x + x1/2y1/2
-----------------
9x + 3x1/2y1/2 - 3x1/2y1/2 - y
3x + x1/2y1/2
−−−−−−−−−−−−
9x - y
Let's try it out for x = 16 and y = 9
Original:
16^(1/2)
-----------
3(4) - 3
4/9
New:
3(16) + 16^(1/2) 9^(1/2)
----------------------
9(16) - 9
----------------------
9(16) - 9
48 + (4)(3)
------------
144 - 9
60/135 = 4/9