# Algebra expression problem

Hi,

I have:

$$\frac{a}{b+a+s} + \frac{c*b}{(b+a+s)(c+s)}$$

I can rearrange that to:

$$\frac{a-c}{b+a-c} * \frac{b+a}{b+a+s} + \frac{b}{b+a-c} * \frac{c}{c+s}$$

Is this correct? If so, can someone tell me why the +s changes into a -c?

## Answers and Replies

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mathman
You should supply the steps. Also what are you trying to achieve?
A simpler expression is (ac + as + bc)/[(b + a + s)(c + s)].

Mark44
Mentor
Hi,

I have:

$$\frac{a}{b+a+s} + \frac{c*b}{(b+a+s)(c+s)}$$

I can rearrange that to:

$$\frac{a-c}{b+a-c} * \frac{b+a}{b+a+s} + \frac{b}{b+a-c} * \frac{c}{c+s}$$

Is this correct? If so, can someone tell me why the +s changes into a -c?
If your goal is to combine the two rational expressions, multiply the one on the left by 1 in the form of (c + s)/(c + s). That gives you the same denominator in both expressions, so you can then add the numerators.

A +s should not change to a -c.