SOLUTION: Solve by completing the square: y^2+5y-2=0 Solve by using the Quadratic Formula 2x^2-4x-9=0

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Question 1022804: Solve by completing the square:
y^2+5y-2=0
Solve by using the Quadratic Formula
2x^2-4x-9=0
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
Solve by completing the square:
y^2 + 5y - 2 = 0
y^2 + 5y + __ = 2
Find the value that completes the square; (5/2)^2 = 6.25
y^2 + 5y + 6.25 = 2 + 6.25
y^2 + 5y + 6.25 = 8.25
factors to
(y + 2.5)(y + 2.5) = 8.25
y + 2.5) = +/-sqrt%288.25%29
y = -2.5 + sqrt%288.25%29
and
y = -2.5 - sqrt%288.25%29
:
Solve by using the Quadratic Formula
2x^2 - 4x - 9 = 0
x+=+%28-b+%2B-+sqrt%28+b%5E2-4%2Aa%2Ac+%29%29%2F%282%2Aa%29+
a=2; b=-4; c=-9
x+=+%28-%28-4%29+%2B-+sqrt%28-4%5E2-4%2A2%2A-9+%29%29%2F%282%2A2%29+
x+=+%284+%2B-+sqrt%2816%2B72+%29%29%2F4+
x+=+%284+%2B-+sqrt%2888%29%29%2F4+
x+=+%284+%2B+9.38%29%2F4+
x = 3.345
and
x+=+%284+-+9.38%29%2F4+
x = -1.345