SOLUTION: im having trouble with 2 radical 7 over 3 radical 5 + 5 radical 3. I know to multiply the top and bottom by 3 radical 5 + 5 radical 3 but what im getting doesnt seem right.

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Question 66452This question is from textbook Algebra 1
: im having trouble with 2 radical 7 over 3 radical 5 + 5 radical 3. I know to multiply the top and bottom by 3 radical 5 + 5 radical 3 but what im getting doesnt seem right. This question is from textbook Algebra 1

Answer by ptaylor(2198) About Me  (Show Source):
You can put this solution on YOUR website!
im having trouble with 2 radical 7 over 3 radical 5 + 5 radical 3. I know to multiply the top and bottom by 3 radical 5 + 5 radical 3 but what im getting doesnt seem right.
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You are on the right track except that you multiply the top and bottom by 3 radical 5 - 5 radical 3. This is called the conjugate and in this case it will get rid of the radicals in the denominator.

2sqrt7/(3sqrt5+5sqrt3) multiply top and bottom by (3sqrt5-5sqrt3) and we get:
(2sqrt7(3sqrt5-5sqrt3))/((3sqrt5+5sqrt3)(3sqrt5-5sqrt3)) multiplying we get:
(6sqrt(7)(5)-10sqrt(7)(3))/(45-75) and this equals
6sqrt(7)(5)-10sqrt(7)(3))/(-30) dividing top and bottom by 2
(3sqrt(7)(5)-5sqrt(7)(3))/-15 factor out sqrt7 in the numerator:
(sqrt7(3sqrt5-5sqrt3))/-15

This should be it---ck using a calculator

Hope this helps----ptaylor