SOLUTION: I just got my SAT test book back and there is one problem that I do not know how to do: The product of a and b is equal to x and the sum of a and b is equal to y. If x and y ar

Question 469796: I just got my SAT test book back and there is one problem that I do not know how to do:
The product of a and b is equal to x and the sum of a and b is equal to y. If x and y are positive numbers, what is 1/a + 1/b in terms of x and y. The answer is y/x but I don't understand how to get that answer. Help!
Thanks.
Answer by ccs2011(207) (Show Source): You can put this solution on YOUR website!
Start with the given
Combine this into 1 fraction, find common denominator
common denominator is ab
-->
Then use substitution:
we know a+b = y and ab = x
-->
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