SOLUTION: the sum of a positive number and twice its square is 6.72. find the number

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Question 540514: the sum of a positive number and twice its square is 6.72. find the number
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
the sum of a positive number and twice its square is 6.72. find the number
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x + 2x^2 = 6.72
Solved by pluggable solver: SOLVE quadratic equation (work shown, graph etc)
Quadratic equation (in our case ) has the following solutons:



For these solutions to exist, the discriminant should not be a negative number.

First, we need to compute the discriminant : .

Discriminant d=54.76 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 1.6, -2.1. Here's your graph:

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It's 1.6


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