Mathematics > Standard Multiple Choice
Read the following SAT test question and then click on a button to select your answer.
If 
and 
, then 
(A) 4
(B) 8
(C) 15
(D) 16
(E) 64
The Correct answer is C.
Explanation
Recall that 
can be factored as 
. Since 
and 
, their product, 
, is 
, or 
.
Another method of solution is to solve the two equations 
and 
simultaneously to get 
and 
. Then 
is 
.