# Math Multiple Choice

If *xy * = 2 and *xy *^{2} = 8, what is the value of *x* ?

- (A) CORRECT ANSWER
- (B) 2
- (C) 4
- (D) 8
- (E) 16

##### Explanation:

Substituting *xy* = 2 into the equation *xy*^{2} = 8, you will obtain (*xy*)*y* = 2*y* = 8, thus *y* = 4. To find *x*, substitute *y* = 4 into one of the two original equations to obtain *x* = . The answer to this problem is (A).

(from the October 17, 1998 test)