SOLUTION: a. Solve using the quadratic formula: x^2-6x-7=0

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Question 143100:
a. Solve using the quadratic formula: x^2-6x-7=0

Answer by jim_thompson5910(35256)   (Show Source): You can put this solution on YOUR website!
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=-6, and c=-7



Negate -6 to get 6



Square -6 to get 36 (note: remember when you square -6, you must square the negative as well. This is because .)



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

Lets look at the first part:



Add the terms in the numerator
Divide

So one answer is




Now lets look at the second part:



Subtract the terms in the numerator
Divide

So another answer is


So our solutions are:
or

Notice when we graph , we get:



and we can see that the roots are and . This verifies our answer

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