SOLUTION: Find the value of r in the quadratic equation: r (to the 2nd power) - 7r - 8 = 0.

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Question 82034: Find the value of r in the quadratic equation:
r (to the 2nd power) - 7r - 8 = 0.
Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
Solved by pluggable solver: SOLVE quadratic equation with variable
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=81 is greater than zero. That means that there are two solutions: .




Quadratic expression can be factored:

Again, the answer is: 8, -1. Here's your graph:
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