Linear Equation Formulas

Greetings,

I am working my way through Algebra 1. Excellent learning resource! My question is to do with the use of the standard formula for linear equations. That formula doesn't seem to be as popular as it's point slope or slope intercept cousins. One reason given was absence of the slope. That is understandable.

I was reading that the slope could be determined from the standard formula using: m = -A/B. I was able to extract the slope using that my method and it agreed with the other formulas.

So it seems, by using standard, I  can easily determine intercepts and slope. I am wondering the reason that: a-the standard form is not used as often as the other 2 and b-the use of -A/B to find slope is not mentioned at all.

I may be answering my own question here, but I also noticed that when extracting  equations from a line, it seemed I was able to create either the slope intercept or point slope equations, but I had to extract the standard equation from one of the other 2. 

Is it possible to extract the standard formula from the graph, and if so how?

I have had a life-long hatred of math...just kidding :). Let's call it pathological suspicion. I found this excellent site while studying for high school equivalency and I'm getting hooked.

Any help and guidance here would be most appreciated.

Thanks,

Graham

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