y=x^2+7x-18
Hopefully you will recognise that this is a parabola because of the xsquared and that is concave up because of the invisible + in front of the xsquared term.
First you try to factorise
You look for two numbers that multiply to -18 and add to 7
since they mult to a negative number, one must be positive and the other negative
since they add to a positive number the bigger one will be the positive one +9 and -2 work.
so
y=(x+9)(x-2)
now to look for some points.
When y=0 either x+9=0 OR x-2=0
When y=0 either x=-9 OR x=2
so 2 points are (-9,0) and (2,0)
Its a parabola so the axis of symmetry is half way between these 2 'roots' that is x=(-9+2)/2 = -3.5
substitute x=-3.5 into the original equation to get the value of y (this will give you the vertex)
It is also easy to find the y intercept. The equation of the y axis is x=0 so substitute x=0 into the original equation and you will get y=-18
now you have 4 points and you know its a parabola so you can graph it.
+118654 
