# Thread: Adding and Subtracting Algebraic Fractions

1. ## Adding and Subtracting Algebraic Fractions

Hi how do you solve these two questions? Simplify the following:

(both attached)

Thanks.

2. ## Re: Adding and Subtracting Algebraic Fractions

Hey jeremyjezzanba.

You can't really solve these equations since there is nothing to compare them to: comparisons need either an inequality (like > or <) or an equality (i.e. = ).

You just have an expression which means nothing: if you make it equal to something or give it an inequality then this is a different thing but as it stands you can't solve anything.

You can simplify these but that's different: simplifying fractions of A/B + C/D is basically using the rule [AD+BC]/BD. Have you covered this in class before?

3. ## Re: Adding and Subtracting Algebraic Fractions

yeh sorry i didn't mean solve i meant simplify. We have very briefly but it is a broad topic so this exact part hasn't been covered. If i could just get a worked example of them i would be able to work others out, thanks.

4. ## Re: Adding and Subtracting Algebraic Fractions

So for the first one you have 1/(x-5) - 3/(x+4) = [x+4 - 3(x-5)]/[(x+4)(x-5)] = (19 - 2x)/[(x-4)(x-5)]

Edited: For typo

5. ## Re: Adding and Subtracting Algebraic Fractions

thankyou but it is X+4 and it is not the right answer

6. ## Re: Adding and Subtracting Algebraic Fractions

Originally Posted by jeremyjezzanba
thankyou but it is X+4 and it is not the right answer
chiro made a typo, but you should be able to take what was provided, change x-4 to x+4 and combine the fractions yourself

7. ## Re: Adding and Subtracting Algebraic Fractions

yes thanks I got it in the end but Still can't work out the second question

8. ## Re: Adding and Subtracting Algebraic Fractions

note that x-2 = -(2-x)

9. ## Re: Adding and Subtracting Algebraic Fractions

I understand that I just don't get the method

10. ## Re: Adding and Subtracting Algebraic Fractions

$\displaystyle \frac{3}{x-2} + \frac{4}{2-x} = \frac{3}{x-2} + \frac{-4}{-(2-x)}$

11. ## Re: Adding and Subtracting Algebraic Fractions

is this correct?

12. ## Re: Adding and Subtracting Algebraic Fractions

no.

$\displaystyle \frac{3}{x-2} + \frac{4}{2-x} = \frac{3}{x-2} + \frac{-4}{-(2-x)} = \frac{3}{x-2} + \frac{-4}{x-2} = \frac{3-4}{x-2} = \frac{-1}{x-2}$