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Factoring for math ?
I need to solve this word problem using factoring. PLEASE dont just give me the answer by using guess and check. I need to see how you do it.
Find two numbers that total 12 and whose squares total 90.
2 Answers
- Anonymous1 decade agoFavorite Answer
Find two numbers that total 12
1) x + y = 12
y = 12 - x
and whose squares total 90.
2) x^2 + y^2 = 90
x^2 + (12 - x)^2 = 90 {substitute for y from equation 1}
x^2 + 144 - 24x + x^2 = 90
2x^2 - 24x + 54 = 0
x^2 - 12x + 27 = 0
Factors of +27 that add to - 12 are -3 & -9
(x - 3)(x - 9) = 0
x = 3, 9
One number is 3, the other is 9
check
3^2 + 9^2 = 90
9 + 81 = 90
90 = 90
