Question

$( \frac{x}{5} - 5).( \frac{x}{5 } + 5) = 0$

Answer 1

$({x\over5}-5)({x\over5}+5)=0\\ \\ ({x\over5})^2}-5^2=0\\ \\ {x^2\over25}-25=0\\ \\ x^2-625=0\\ \\ x=\pm\sqrt{625} \\ \\ x=\pm25$