Question

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

Answer 1

`x=7/4` is the axis of symmetry
`(7/4,-113/8)` is the minimum
y intercept is -8

Explanation:

It is a positive `x^2` so it will be a `uu` shaped parabola

`(-b)/(2a)` will give the x coordinate of the vertex

`7/4`

Put this into the equation to find the y coordinate

`2xx(7/4)^2-7xx7/4-8`

`98/16-49/4-8=-113/8=-12 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