1. ## 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...

2. ## Re: Basic Algebra...

Well b-a=-(a-b) so you have

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

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

any ideas from there?

By the way it's not an equation.

3. ## 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

4. ## Re: Basic Algebra...

In English these are called 'expressions'

5. ## Re: Basic Algebra...

thanks ) do you know how I can simplify the second expression?

6. ## Re: Basic algebra

Originally Posted by keepmymemory
do you know how I can simplify the second expression?
Instead of expanding, factorize the numerator and the denominator.

7. ## Re: Basic algebra

Thank you! It worked