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**Plato** Will you take: $ \underline{+4a+c-7 \sqrt{b}-5}$

OR does it need separation: $\underline{+4a}\;$$ \underline{+c}\:$ $\underline{-7 \sqrt{b}}\;$$ \underline{-5}\;$

Hi Plato, thanks for the reply. The second example would be perfect, although I'm a little confused by the syntax so I cannot modify it to suit my needs. Basically, in my assignment I am explaining how to solve a quadratic equation. Here is the part where I need to use underline:

Code:

Now we group the four terms into pairs and take out common factors:
\begin{align*}
3x^2 + 2x -8 &= \underline{3x^2 + 6x} \underline{- 4x -8}\\
&= 3x(x+2) - 4(x + 2)\\
&= (3x - 4)(x + 2)
\end{align*}

So on the first line in the {align*} blocks, the term pairs "3x^2 + 6x" and "-4x - 8" would be seperately underlined. I modified your second example and made it display what I wanted outside of the {align*} block, but when I try putting it into the block it fails to compile. Any ideas?

Edit: Never mind, I just worked it out

Code:

Now we group the four terms into pairs and take out common factors:
\begin{align*}
3x^2 + 2x -8 &= \underline{3x^2 + 6x} \text{ } \text{ } \underline{- 4x -8}\\
&= 3x(x+2) - 4(x + 2)\\
&= (3x - 4)(x + 2)
\end{align*}

Looks just how I wanted, thanks for your help!