Let the two numbers are x and y.chieftang wrote:The product of two positive numbers is 9 and the sum of their squares is 31. What is their sum?
(A) 5
(B) 6
(C) 7
(D) 8
(E) 9
OA: To be given after discussion.
Then xy = 9 and x² + y² = 31, so we have to find x + y.
Now we know that, (x + y)² = x² + y² + 2xy
So, (x + y)² = 31 + 2(9)
(x + y)² = 49
x + y = 7
The correct answer is C.
