SOLUTION: The product of two numbers is 640. Their difference is 12. Find these numbers.

Question 964446: The product of two numbers is 640. Their difference is 12. Find these numbers.
Found 2 solutions by addingup, Alan3354:
Answer by addingup(3677) (Show Source): You can put this solution on YOUR website!
let's call the numbers a and b:
ab= 640
a-b= 12 and therefore a= 12+b Substitute in the first equation:
b(12+b)= 640
12b+b^2= 640 We now have a quadratic binomial:
b^2+12b-640= 0 factor the equation
(b+32)(b-20)= 0 Now solve each separately:
b+32= 0 or b-20= 0
b= -32 or b= 20 We toss out the negative and keep the 20
So, one number is 20 and the other is 640/20= 32.
Proof:
32*20= 640 and
32-20 = 12
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Try pairs of factors of 640, find 2 factors that differ by 12.
--------
1*640 NG
2*320 NG
etc.

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