Hiya people I'm new around here..butI've got a major problem

I'm doin ccompSi. A-levels and my project is an equation plotter..

the thing is I'm used to using Quickbasic. and wellI'm plotting graphs using the circle staement which is pretty bad I know but I coul'dnt think of anything else
anyway this works fine when I'm plotting straight line (y=mx+c) but with quadratic equations it look so crappy and bad...don'tsupposeany1 could help me with this...

and another thing in QB I used aterm window so I could set my own sort of like frame and well set my own range for x and y.this is useful cuz I can let the user change it..but I don't think it works in VB...Puh-lease any1 with any info I'd love to here it...!!