Hi Mike, sorry for asking questions so frequently. I’m on my 16th practice test now and I am amazed to find something new everytime. Anyway…

If x and y are numbers such that (x+9)(y-9)=0 what is the smallest possible value of X^2 + y^2

A 0

B 9

C 18

D 81

E 162I got E when I did this but the answer is 81.Why?

If (*x* + 9)(*y* – 9) = 0, then either *x* = –9 or *y* = 9, but those don’t BOTH have to be true. To minimize , assume that one of them is equal to 0.

For example, say *x* = 0, and *y* = 9. Then (*x* + 9)(*y* – 9) = 0, and .