How do you identify the vertex of the parabola defined by #y=2x^2+8x+9#?

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Answer 1 · 2016-12-30T08:11:41

#V(-2;1)#

The vertex x-coordinate is calculated by

#x_V=-b/(2a)#

where #a=2 and b=8#

that's

#x_V=-8/4=-2#

You can calculate its y-coordinate by simply substituting in the parabola's equation:

#y_V=2(-2)^2+8(-2)+9#

#=8-16+9=1#

Then the vertex is #V(-2;1)#