SOLUTION: a number is 72 less than its square. Find all such numbers.

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Question 308581: a number is 72 less than its square. Find all such numbers.
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
let the number be x
x^2 -72 =x
x^2-x-72=0
x^2_9x+8x-72=0
x(x-9)+8(x-9)=0
(x+8)(x-9)=0
x= -8 OR x= 9