SOLUTION: Find a number such that one half of it's square is equal to twice the number plus 8?

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Question 390943: Find a number such that one half of it's square is equal to twice the number plus 8?
Answer by mananth(16946) About Me  (Show Source):
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Find a number such that one half of it's square is equal to twice the number plus 8?
...
Let number be x
1/2 *(x^2)=2x+8
multiply by 2
x^2=2(2x+8)
x^2=4x+16
x^2-4x-16=0
...
use quadratic formula to find the roots of the equation
x=%28-b%2B-sqrt%28b%5E2-4ac%29%29%2F2a
a=1,b=-4,c=16
b^2-4ac=80
...
x1=%28-b%2Bsqrt%2880%29%29%2F2
%28highlight%28x1=6.47%29%29
x2=%28-b-sqrt%2880%29%29%2F2
%28highlight%28x2=-2.47%29%29
...
m.ananth@hotmail.ca