SOLUTION: Solve by using the quadratic formula. x^2 = 5x + 8

Question 88259: Solve by using the quadratic formula. x^2 = 5x + 8

Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!

Get everything to one side

Now let's use the quadratic formula to solve for x:

Starting with the general quadratic

the general form of the quadratic equation is:

So lets solve (notice , , and )

Plug in a=1, b=-5, and c=-8

Negate -5 to get 5

Square -5 to get 25

Multiply to get

Combine like terms in the radicand (everything under the square root)

Simplify the square root

Multiply 2 and 1 to get 2

So now the expression breaks down into two parts

or

Which approximate to

or

So our solutions are:
or

Notice when we graph we get:

when we use the root finder feature on a calculator, we find that and .So this verifies our answer.
RELATED QUESTIONS
solve by using the quadratic formula?... (answered by checkley75)

Solve by using the quadratic formula. 5x^2 + x = 3 (answered by jim_thompson5910,malakumar_kos@yahoo.com)

Solve by using the quadratic formula. 5x^2 + x = 3 (answered by malakumar_kos@yahoo.com)

Solve by using the quadratic formula. 5x^2 + x = 3 (answered by Edwin McCravy)

Solve by using the quadratic formula. x^2 = �5x � 5 (answered by jim_thompson5910)

Solve by using the quadratic formula x^2 = �5x �... (answered by jim_thompson5910)

Solve by using the quadratic formula. x^2 = �5x � 5 (answered by edjones)

Solve by using the quadratic formula 5x^2 + x =... (answered by jim_thompson5910)

solve by using the quadratic formula? 5x^2+5x=3 (answered by jim_thompson5910)