TeX Quellcode:
{\dfrac{1}{14x+15z} : \dfrac{14x-15z}{196x^2-225z^2} = \dfrac{1}{14x+15z} \cdot \dfrac{196x^2-225z^2}{14x-15z} = \dfrac{196x^2-225z^2}{\left(14x+15z\right)\left(14x-15z\right)} = \dfrac{\left(14x+15z\right)\left(14x-15z\right)}{\left(14x+15z\right)\left(14x-15z\right)} = 1}