\begin{align*} ax^{2} + bx + c = 0 & \Longleftrightarrow 4a^{2}x^{2} + 4abx + 4ac = 0\\\\ & \Longleftrightarrow (4a^{2}x^{2} + 4abx + b^{2}) = b^{2} - 4ac \tag{2}\\\\ & \Longleftrightarrow (2ax + b)^{2} = b^{2} - 4ac\\\\ & \Longleftrightarrow 2ax + b = \pm\sqrt{b^{2} - 4ac}\\\\ & \Longleftrightarrow x = \frac{-b \pm \sqrt{b^{2} - 4ac}}{2a} \end{align*}
how does in step-2 4abx simplified to b. if it is divided by 4ax then it should be on both side. step-2 can someone explain it in detail?