SOLUTION: four times the square of a number is 21 more than eight times the number. what is the number?

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Question 422920: four times the square of a number is 21 more than eight times the number. what is the number?
Answer by ewatrrr(24785)   (Show Source): You can put this solution on YOUR website!

Hi
Let x represent the number
Question states***Write as we Read
4x^2 = 8x + 21
Solving for x
4x^2 - 8x - 21 = 0


x =
x = 28/8 = 7/2
or x = -12/8 = - 3/2
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