Questions About How To Add Fractions With Variables

Charles asks…

How to add and subtract fractions with variables in them?

Mmkay I am not looking for answers just how to do the problem, I need to show my work on this packet anyway. Ok so the problems are....

1) 7n - 5n/c5.
2) 2x/9 + 1x/12

Thanks! I know that you need a common denominator and after I do that would I add straight across and just add the variable? Thanks, again!

admin answers:

Find a common denominator, then just multiple the whole equation by it. E.g.,

3x/4 + 1x/8 = 1
6x/8+1x/8 = 1
6x+1x=8
7x=8
x=8/7

Thomas asks…

can anyone show me how to add fractions with variables?

im having trouble adding these fractions with variables can anyone give me the answer and the steps to do it or a link to a site that will teach me how?
3/a^2 + 6/5a
3/x-5 +x-1/x

admin answers:

You need to get a common denominator then add the tops just like regular fractions.
On the first the LCD is 5a^2 so multiply top and bottom of the first by 5/5, and the second by a/a
15 / 5a^2 + 6a / 5a^2 which is just (15 + 6a) / 5a^2

And on the other it's not clear what the denominators are,
but if they are (x - 5) and (x) the LCD is (x - 5)x
so top and bottom of first by x/x and second by (x - 5)/(x - 5)
3x / (x+5)x + (x-1)(x+5) / (x+5) / x

3x + x^2 + 4x - 5 over (x+5)x

x^2 + 7x - 5 over (x+5)x

Laura asks…

How do you add/subtract fractions with variables?

I need to know for my homework. Here's one of the problems:

3r/10 + 3r/10
Thanks! Just got a little stumped there over my long weekend of playing MW3!

admin answers:

6r/10 = 3r/5

Same way you'd add/subtract normal fractions; just the variables have to be the same.

3r/10 + 3r/10 = 6r/10 = 3r/5

3r/10 + 3x/10 = 3r+3x/10 (You can't do it because you can't add r and x together).

James asks…

Can someone show me how to add these fractions WITH variables?

5/8x + 1/16x = 3/16 + x

The LCD is 16... but I'm not sure where to go from there.

admin answers:

5/8x + 1/16x = 3/16 + x you found that the common denominator to use is 16

10/16x I multiplied the first term with 2/2 to get the denominator to 16

10/16x + 1/16x = 3/16 + 16/16x <----------this is the same as x or one x

11/16x = 3/16 + 16/16x I combined like terms on the left of the equal sign

now minus 16/16x to both sides of equal sign

-5/16x = 3/16 to remove the -5/16 from the x...you need to multiply both sides by it reciprocal, which is -16/5

x = 3/5 or 0.6

good luck

John asks…

How to add/subtract fractions with variables?

How do you simplify and expression like
(x^2+15x-4)/ (x^2-x-2) + (x^2-x-32)/(x^2-x-2) ????

admin answers:

Since there is a common denominator, we can add the numerators:

((x^2 + 15x - 4) + (X^2 - x - 32))/(X^2 - x - 2) = (2x^2 + 14x - 36)/(X^2 - x - 2)

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