Thread: If C=A+A*B what's A in terms of B & C?

I find myself in the odd situation of actually having to use algebra in real life many many years after leaving school!

If C = A + A * B, how do I find A from knowing B and C? If it makes any difference, A,B & C are all greater than zero.

Originally Posted by rbbot

I find myself in the odd situation of actually having to use algebra in real life many many years after leaving school!

If C = A + A * B, how do I find A from knowing B and C? If it makes any difference, A,B & C are all greater than zero.

I'll take as A times B.

, the left hand side of this equation has common factor A, we can therefore write it as:

, then dividing both sides by ,



Hope this helps

The thing to remember here, is that your equation is equivalent to , and then you clearly see the common factor. As you practice more and more, it will become a reflex.

Thanks

Why can't you just subtract the product of (A*B) from C? Would this be wrong?
I don't think my method would answer his question because it doesn't simply the equation to A in terms of B and C (it is A in terms of A,B, and C) amd I right?

So...
C = A + (AB) -> (-AB)
C - AB = A

Originally Posted by Masterthief1324

Why can't you just subtract the product of (A*B) from C? Would this be wrong?
I don't think my method would answer his question because it doesn't simply the equation to A in terms of B and C (it is A in terms of A,B, and C) amd I right?

So...
C = A + (AB) -> (-AB)
C - AB = A

You can do that, but where does it get you? The thing here is that we were asked to "find A given B and C". The word "find" implies that we should solve for A.

Originally Posted by Masterthief1324

I don't think my method would answer his question because it doesn't simply the equation to A in terms of B and C (it is A in terms of A,B, and C) amd I right?

correct.