SOLUTION: X^2-4x-7=0

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Question 935082: X^2-4x-7=0
Answer by MathLover1(20849) About Me  (Show Source):
You can put this solution on YOUR website!

x%5E2-4x-7=0...use quadratic formula to find x

x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+ ...since a=1,b=-4, and c=-7 we have
x+=+%28-%28-4%29+%2B-+sqrt%28+%28-4%29%5E2-4%2A1%2A%28-7%29+%29%29%2F%282%2A1%29+
x+=+%284+%2B-+sqrt%28+16%2B28+%29%29%2F2+
x+=+%284+%2B-+sqrt%28+44+%29%29%2F2+
x+=+%284+%2B-+sqrt%28+4%2A11+%29%29%2F2+
x+=+%28cross%284%292+%2B-+cross%282%29%2Asqrt%28+11+%29%29%2Fcross%282%29+
x+=+%282+%2B-+sqrt%28+11+%29%29+
exact solutions:
x+=+2+%2B+sqrt%28+11+%29+
x+=+2+-+sqrt%28+11+%29+
approximate solutions:
x+=+2+%2B+3.3+=5.3
x+=+2+-+3.3=-1.3+
+graph%28+600%2C+600%2C+-10%2C+10%2C+-10%2C+10%2C+x%5E2-4x-7%29+