I have an equation $$\vec E = \frac{1}{4 \pi \epsilon_{0}} * \frac{Q}{x * \sqrt{x^2+a^2}}$$
where $\lambda = Q / 2a$
And this equation is rewritten into $$\vec E = \frac{1}{2 \pi \epsilon_{0}} * \frac{\lambda}{x * \sqrt{(x^2/a^2)+1}}$$
I tried to divide it by $a$ but couldn't continue. I need some explanation on how it is rewritten.
$$\begin{align} \vec E & = \frac{1}{4 \pi \varepsilon_{0}} \frac{Q}{x \cdot \sqrt{x^2+a^2}} \qquad [Q = 2a\lambda]\\[6pt] & = \frac{1}{4 \pi \varepsilon_{0}} \frac{2a\lambda}{x \cdot \sqrt{x^2+a^2}} \\[6pt] & = \frac{1}{2 \pi \varepsilon_{0}} \frac{\lambda}{\frac{x}{a} \cdot \sqrt{x^2+a^2}} \\[6pt] & = \frac{1}{2 \pi \varepsilon_{0}} \frac{\lambda}{x \cdot \sqrt{\frac{x^2}{a^2}+\frac{a^2}{a^2}}} \end{align}$$