Multi-row text comment in align environment

Question

I am wondering what is the best way to make multi-row text comments in the align environment. Here is an example code:

\begin{align*}
\int \left( \frac{x+3}{2}\right) \, dx =& \int \frac{1}{2}(x+3) \, dx & \text{Factoring out a constant.} \\
 =& \frac{1}{2} \int (x+3) \, dx & \text{Factoring the constant outside the integral} \\
 =& \frac{1}{2}[\frac{1}{2}x^2+3x]+C & \text{Applying the power rule and adding the constant of integration} \\
 =& \frac{1}{4}x^2+\frac{3}{2}x+C & \text{Distributing the } \frac{1}{2} \\
 =& \frac{x^2+6x}{4}+C& \text{Finding a common denominator} \\
 =& \frac{x(x+6)}{4}+C & \text{Factoring out an } x
 \end{align*}

I am not very fond of the way the comment is close to the equation in the third line where it says "applying the power rule...", is there any neat way of making a 2 line comment that doesn't look awkward?

Answer 1

Using amsmath package the code:

---

Method 1:

\begin{align*}
\int \left( \frac{x+3}{2}\right) \, dx
=& \int \frac{1}{2}(x+3) \, dx && \text{Factoring out a constant} \\
=& \frac{1}{2} \int (x+3) \, dx && \text{Factoring the constant outside the integral} \\
=& \frac{1}{2}\left[\frac{1}{2}x^2+3x\right]+C && \text{Applying the power rule and }\\ 
 &  && \text{adding the constant of integration} \\
=& \frac{1}{4}x^2+\frac{3}{2}x+C && \text{Distributing the } \frac{1}{2} \\
=& \frac{x^2+6x}{4}+C && \text{Finding a common denominator} \\
=& \frac{x(x+6)}{4}+C && \text{Factoring out an }
\end{align*}

produces a nice aligned set as seen by:

---

Method 2: Using Barbara Beeton's \parbox suggestion:

\begin{align*}
\int \left( \frac{x+3}{2}\right) \, dx
=& \int \frac{1}{2}(x+3) \, dx && \text{Factoring out a constant} \\
=& \frac{1}{2} \int (x+3) \, dx && \text{Factoring the constant outside the integral} \\
=& \frac{1}{2} \left[ \frac{1}{2}x^2+3x \right]+C && \parbox{5.5cm}{Applying the power rule and 
                                                             adding the constant of integration} \\
=& \frac{1}{4}x^2+\frac{3}{2}x+C && \text{Distributing the } \frac{1}{2} \\
=& \frac{x^2+6x}{4}+C && \text{Finding a common denominator} \\
=& \frac{x(x+6)}{4}+C && \text{Factoring out an }
\end{align*}