SOLUTION: if seven is added to two times a number, the result is eight less than the square of the number. Find all such numbers?

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Question 807784: if seven is added to two times a number, the result is eight less than the square of the number. Find all such numbers?
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let number be x
2 times a number = 2x
7 added to it
2x+7
square of number = x^2
8 less
x^2-8
2x+7 = x^2-8
x^2-2x-15=0
x^2-5x+3x-15=0
x(x-5)+3(x-5)=0
(x-5)(x+3)=0
x=5 OR x=-3