Vertex of a parabola

What is the vertex of the parabola y = x² + 8x + 5  ?

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y = x² + 8x + 5
a = 1, b = 8, and c = 5   {in standard form}

-b
---- is the x-coordinate of the vertex
2a

 -8
------  = x-coordinate of vertex  {substituted 1 for a and 8 for b}
2(1)

x-coordinate of vertex is -4   {simplified}

y = x² + 8x + 5   {the equation of the parabola}
y = (-4)² + 8(-4) + 5   {substituted -4 for x into equation to find y-coordinate of vertex}
y = 16 - 32 + 5   {evaluated exponent and multiplied}
y = -11   {added and subtracted}

(-4 , -11) is the vertex of the parabola

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