The product of the squares of two positive integers is 1600. How many pairs of positive integers satisfy this condition?  Choices.
A) 0  B) 1  C) 2  D) 3  E) 4
Ans: E - 4 pairs   (xˆ2)(yˆ2) = 1600 [square root both sides]   xy = 40   40 = 1x40, 4x10, 40x1, 10x4, 5x8, 8x5, 20x2, 2x20   Cancel the repeats   This leaves us with exactly 4 options.   Hence, 4
<result>E</result>
The product of the squares of two positive integers is 1600. How many pairs of positive integers satisfy this condition?