SOLUTION: X^2-X=56 using quadratic fomula

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Question 680827: X^2-X=56 using quadratic fomula
Found 3 solutions by ReadingBoosters, MathTherapy, JBarnum:
Answer by ReadingBoosters(3246) About Me  (Show Source):
You can put this solution on YOUR website!
x%5E2+-+x+=+56
x%5E2+-+x+-+56+=+0
...
x+=+%28-1%2B-sqrt%28-1%5E2-4%281%29%28-56%29%29%29%2F%282%2A1%29
x+=+%28-1%2B-sqrt%281%2B224%29%29%2F2
x+=+%28-1%2B-sqrt%28225%29%29%2F2
x+=+%28-1%2B-15%29%2F2
...
x+=+%28-1%2B15%29%2F2+=+%2814%2F2%29+=highlight_green%287%29
AND
x+=+%28-1-15%29%2F2+=+%28-16%2F2%29+=highlight_green%28-8%29
.....................
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Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

X^2-X=56 using quadratic fomula

Using the quadratic formula, you should get: highlight_green%28x+=+-+7%29, or highlight_green%28x+=+8%29

Answer by JBarnum(2146) About Me  (Show Source):
You can put this solution on YOUR website!
This is actually a mental problem you can solve in seconds while remembering ax%5E2%2Bbx%2Bc
x%5E2-x-56=0 find 2 numbers that add to (b) and multiply to get (c)
-8 and 7
Now take the opposite of those numbers to find what x is equal too
X= 8,-7