SOLUTION: Use the qadratic formula to find the solutions to the equation. -x^2-x=7

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Question 289785: Use the qadratic formula to find the solutions to the equation. -x^2-x=7
Answer by j1mmy94(14) About Me  (Show Source):
You can put this solution on YOUR website!
The original quadratic equation: +-x%5E2-x=7+
First you have to get the quadratic equation to equal to 0.
So you have to subtract 7 on both sides. You should get +-x%5E2-x-7=0+
It doesn't seem like the quadratic equation can be easily factored.
We have to use the quadratic formula which is x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
In our case,
a= -1
b= -1
c= -7
Plug in the values for the variables.
x+=+%28-%28-1%29+%2B-+sqrt%28+%28-1%29%5E2-4%2A-1%2A-7+%29%29%2F%282%2A-1%29+
Simplify the equation:
x+=+%281+%2B-+sqrt%28+1-28+%29%29%2F%28-2%29+
x+=+%281+%2B-+sqrt%28+-27+%29%29%2F%28-2%29+
The discriminant is less than zero, we can now tell that the solutions are imaginary and should include the symbol i.
x+=+%281+%2B-+3+i+sqrt3+%29%2F%28-2%29+
x+=+-1%2F2+%2B-+%283%2F2%29i+sqrt3++