SOLUTION: If the square of a number is added to 3 times the number,the sum is 108.Find the number.

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Question 1190247: If the square of a number is added to 3 times the number,the sum is 108.Find the number.
Answer by greenestamps(13200) About Me  (Show Source):
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The words say

3x%2Bx%5E2=108

That's a quadratic equation; get everything on one side and factor:

x%5E2%2B3x-108=0

With a negative constant term, the factorization has to be of the form (x+a)(x-b); so we need two numbers whose product is 108 and whose difference is 3 -- 12 and 9.

%28x%2B12%29%28x-9%29=0
x=-12 or x=9

Check to see if both solutions to the equation are solutions to the original problem:
x=-12: 3x+x^2 = -36+144 = 108 check
x=9: 3x+x^2 = 27+81 = 108 check

ANSWERS: -12 or 9