- TeX source:
- \begin{array}{rclcl} 5x^2-38x+225 &=& 4x^2-8x & \vert & -4x^2+8x \cr x^2-30x+225 &=& 0 \cr x_{1,2} &=& -\dfrac{-30}{2}\pm\sqrt{\left(\dfrac{-30}{2}\right)^2-225} \cr x_{1,2} &=& 15\pm\sqrt{0} \cr x_{1,2} &=& 15 \cr \cr \mathbb{L} &=& \{15\} \end{array}