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

Dec 30, 2016

#### Answer:

V(-2;1)

#### Explanation:

The vertex x-coordinate is calculated by

${x}_{V} = - \frac{b}{2 a}$

where $a = 2 \mathmr{and} b = 8$

that's

${x}_{V} = - \frac{8}{4} = - 2$

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

${y}_{V} = 2 {\left(- 2\right)}^{2} + 8 \left(- 2\right) + 9$

$= 8 - 16 + 9 = 1$

Then the vertex is V(-2;1)