SOLUTION: y+x^2=-(8x+23) Write in vertex form and find axis of symmetry

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Question 970912: y+x^2=-(8x+23) Write in vertex form and find axis of symmetry
Found 2 solutions by stanbon, Boreal:
Answer by stanbon(75887) (Show Source):
You can put this solution on YOUR website!
y+x^2=-(8x+23) Write in vertex form and find axis of symmetry
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y = -x^2-8x-23
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y = -(x^2+8x)-23
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-(x^2+8x+16) = y+23-16
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-(x+4)^2 = y+7
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Vetex:: (-4,-7)
Axis of symmetry:: x = -4
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Cheers,
Stan H.

Answer by Boreal(15235) (Show Source):
You can put this solution on YOUR website!
y+x^2=-(8x+23)
y=-x^2-8x-23 = -(x^2+8x+23)
Complete the square -(x^2+8x +16). Have added -16 to the equation, have to add 16 to the constant outside, now so -23 +16 =-7
y=-(x+4)^2-7
Let's check this.
y= - {x^2+8x +16)-7 This is -x^2-8x-23, which is what we had.
a=-1, the coefficient of x.
The vertex x value is -b/2a = - (-8)/(-2) =-4
THE AXIS OF SYMMETRY IS THE LINE X= -4
If x= -4 y=-7
Vertex form y= a (x-h)^2 +k
y = -1(x+4)^2 -7