How to cross out long terms

Jonboy · #1 $Old$ 07-28-2008, 07:59 PM

How to cross out long terms?

Like this: $\frac{\rlap{---------}(x + 5)(x - 2)}{\rlap{---------}(x + 5)} = x - 2$

This is something I've been wanting to do again for a while but forgot. And I couldn't find it anywhere. Here's what I've found through experimentation.

You use: \rlap {--}

In front of the term where you want the slash to start.

Then increase the "-" between the brackets until it's long enough.

Is there an easier way to do this? I imagine so.

Soroban · #2 $Old$ 07-30-2008, 02:50 PM

I experimented with Jonboy's suggestion . . .

It seems that "rlap" is an over-write command.

\rlap{///}3x^2 . $\Rightarrow\quad \rlap{///}3x^2$

\rlap{TRUE}false . $\Rightarrow\quad \rlap{TRUE}false$

\rlap{|}X . $\Rightarrow\quad \rlap{|}X$

\rlap{||}\:5T^2 . $\Rightarrow\quad \rlap{||}\:5T^2$

I don't know why "|" produces a horizontal line.

Jonboy · #3 $Old$ 07-30-2008, 03:55 PM

Thanks for the response Soroban! Very interesting findings.

wingless · #4 $Old$ 07-30-2008, 05:44 PM

It would be much easier if we had the cancel package in LaTeX...

earboth · #5 $Old$ 07-31-2008, 12:04 AM

Quote:

Originally Posted by Jonboy $View Post$

How to cross out long terms?

Like this: $\frac{\rlap{---------}(x + 5)(x - 2)}{\rlap{---------}(x + 5)} = x - 2$

...

With Jonboy's method you can use different colours to cross out different terms.

$\frac{\bold{\rlap{{\color{red}====}}}(x + 5)(x - 2) \rlap{{\color{blue}---------}}(x + 7)}{\rlap{{\color{red}====}}(x + 5) \rlap{{\color{blue}---------}}(x + 7)} = \bold{x - 2}$

It would be nice and much more legible if the horizontal line could be printed in bold style. Unfortunately I didn't find the appropriate command

. The \bold{..} obviously only works with numbers and letters.

Opalg · #6 $Old$ 10-26-2008, 05:38 AM

Quote:

Originally Posted by earboth $View Post$

With Jonboy's method you can use different colours to cross out different terms.

$\frac{\bold{\rlap{{\color{red}====}}}(x + 5)(x - 2) \rlap{{\color{blue}---------}}(x + 7)}{\rlap{{\color{red}====}}(x + 5) \rlap{{\color{blue}---------}}(x + 7)} = \bold{x - 2}$

It would be nice and much more legible if the horizontal line could be printed in bold style. Unfortunately I didn't find the appropriate command

. The \bold{..} obviously only works with numbers and letters.

Using \vrule, you can create lines of any height, depth and width that you want. For example, $\frac{(\rlap{\color{red}\vrule height3.5pt depth-2pt width2.3em}x + 5)(x - 2) (\rlap{\color{blue}\vrule height3.5pt depth-2pt width2.3em}x + 7)}{(\rlap{\color{red}\vrule height3.5pt depth-2pt width2.3em}x + 5) (\rlap{\color{blue}\vrule height3.5pt depth-2pt width2.3em}x + 7)} = x - 2$ comes from this code:

Code:

\frac{(\rlap{\color{red}\vrule height3.5pt depth-2pt width2.3em}
x + 5)(x - 2) (\rlap{\color{blue}\vrule height3.5pt depth-2pt width2.3em}
x + 7)}{(\rlap{\color{red}\vrule height3.5pt depth-2pt width2.3em}
x + 5) (\rlap{\color{blue}\vrule height3.5pt depth-2pt width2.3em}
x + 7)} = x - 2