# How do you find the axis of symmetry, graph and find the maximum or minimum value of the function y=2x^2-7x-8?

##### 1 Answer
Jun 17, 2018

$x = \frac{7}{4}$ is the axis of symmetry
$\left(\frac{7}{4} , - \frac{113}{8}\right)$ is the minimum
y intercept is -8

#### Explanation:

It is a positive ${x}^{2}$ so it will be a $\cup$ shaped parabola

$\frac{- b}{2 a}$ will give the x coordinate of the vertex

$\frac{7}{4}$

Put this into the equation to find the y coordinate

$2 \times {\left(\frac{7}{4}\right)}^{2} - 7 \times \frac{7}{4} - 8$

$\frac{98}{16} - \frac{49}{4} - 8 = - \frac{113}{8} = - 12 \frac{1}{8}$

Construct a table of values, putting values of x into the equation to get the relevant y values in order to plot the graph.
Use values between -2 and 2 for x