SOLUTION: log base8 [(x+8)(x+9)]=2

Question 527085: log base8 [(x+8)(x+9)]=2
Answer by nerdybill(7384) (Show Source): You can put this solution on YOUR website!
log base8 [(x+8)(x+9)]=2
(x+8)(x+9) = 8^2
x^2+17x+72 = 64
x^2+17x+8 = 0
apply the "quadratic formula" to get:
x = {-0.484, -16.516}
we can throw out the -16.516 (extraneous) leaving:
x = -0.484
.
details of quadratic:

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=257 is greater than zero. That means that there are two solutions: .

Quadratic expression can be factored:

Again, the answer is: -0.484390229059301, -16.5156097709407. Here's your graph:

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