Question

How do you graph `y=x^2 -4x-21`?

Answer 1

Given -

`y=x^2-4x-21`

Find its `x` coordinate of the vertex

`x=(-b)/(2a)=(-(-4))/(2 xx 1)=4/2=2`

Take a few values on either side of `x=2`
Find corresponding `y` values
Tabulate them

Plot them on a graph sheet. Join them with a smooth curve.