# Basic Algebra...

• Apr 5th 2012, 04:47 AM
keepmymemory
Basic Algebra...
OK, I need help with two pretty basic questions. I keep making the same stupid mistakes. Please help!

Solve to the smallest equation.
1. (a-b)c2 + (b-a)c4

My working out so far:
= c2 [(a-b)+(b-a)c2)]
... then I don't know what to do. I know the answer is c2 (a-b), but how do I get there?

2. (x-y)2 -z2 / (x+z)2 -y2

So it occurs to me to use those math equations like following:
x2 +2xy +y2 -z2 / x2 + 2xz + z2 -y2

And then what? I'm not very good at maths...
• Apr 5th 2012, 04:58 AM
a tutor
Re: Basic Algebra...
Well b-a=-(a-b) so you have

\$\displaystyle (a-b)c^2-(a-b)c^4\$

\$\displaystyle = (a-b)(c^2-c^4)\$

any ideas from there?

By the way it's not an equation.
• Apr 5th 2012, 05:06 AM
keepmymemory
Re: Basic Algebra...
Thanks yeah I can figure it out from there. I don't know what these things are called in English :)) thank you very much
• Apr 5th 2012, 05:38 AM
biffboy
Re: Basic Algebra...
In English these are called 'expressions'
• Apr 5th 2012, 05:57 AM
keepmymemory
Re: Basic Algebra...
thanks :)) do you know how I can simplify the second expression?
• Apr 5th 2012, 06:33 AM
Sylvia104
Re: Basic algebra
Quote:

Originally Posted by keepmymemory
do you know how I can simplify the second expression?

Instead of expanding, factorize the numerator and the denominator.
• Apr 5th 2012, 06:55 AM
keepmymemory
Re: Basic algebra
Thank you! It worked :D