# Really quick question, should be easy for most people

• Mar 28th 2009, 04:44 PM
Torlot
Really quick question, should be easy for most people
Hi,

I have a real quick question. I suck at math and this popped up while finding a derivative. I am not sure if this should be in this part of the board or not, but I am putting it here cause this corresponds to the math level where this popped up.

If I have 3(2x+h)/h, would it be permissible to cancel out the h and leave 3*2x=6x, or is this incorrect?
• Mar 28th 2009, 04:58 PM
Shapeshift
This would be incorrect because if you expand it:

3(2x+h)/h

= (6x + 3h)/h

= 6x/h + 3h/h

= 6x/h +3

The h can only be canceled out if every term in the numerator had an h.
Hope this helps!
• Mar 28th 2009, 05:02 PM
Torlot
Ah, right, I see. I knew something was feeling wrong about it, but didnt know what. I'm not a good math person, but I know when I am prolly doing something wrong. Thank you.

Going back, I think I see where I might've went the wrong way.

I end up with $\displaystyle 6xh+3h^2/h$

Can this be simplified to $\displaystyle 6x+3?$ Cause what I did was just take out the h from the $\displaystyle 3h^2$...
• Mar 28th 2009, 06:27 PM
mr fantastic
Quote:

Originally Posted by Torlot
Going back, I think I see where I might've went the wrong way.

I end up with $\displaystyle 6xh+3h^2/h$

Can this be simplified to$\displaystyle 6x+3?$ Cause what I did was just take out the h from the $\displaystyle 3h^2$...

$\displaystyle \frac{6xh + 3h^2}{h} = \frac{h (6x + 3h)}{h} = \frac{\not{h} (6x + 3h)}{\not{h}} = 6x + 3h$.

It would be better if you posted the whole question ..... Otherwise who knows whether you're even meant to have $\displaystyle \frac{6xh + 3h^2}{h}$ as part of the working ....