SOLUTION: Use the Quadratic Formula to solve the equation. –x^2 + 7x = 8

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Question 700974: Use the Quadratic Formula to solve the equation.
–x^2 + 7x = 8
Found 2 solutions by MathLover1, josmiceli:
Answer by MathLover1(20849)   (Show Source): You can put this solution on YOUR website!
....write it in standard form

Solved by pluggable solver: Quadratic Formula
Let's use the quadratic formula to solve for x:


Starting with the general quadratic





the general solution using the quadratic equation is:







So lets solve ( notice , , and )





Plug in a=-1, b=7, and c=-8




Square 7 to get 49




Multiply to get




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




Simplify the square root (note: If you need help with simplifying the square root, check out this solver)




Multiply 2 and -1 to get -2


So now the expression breaks down into two parts


or



Now break up the fraction



or



Simplify



or



So the solutions are:

or



Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!


The quadratic formula finds 2 values for
called the roots that satisfy this equation.
The equation has to be in the general form

For your equation:



----------







and



--------------
Check the solutions




close enough



OK
Here's the plot of the equation:
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