Решить уравнения 1/4х2-1=0; 4/5х2-45=0; х2-16=0 желательно расписать

Решите задачу:

$\frac{1}{4} x^{2} -1=0\\\\ \frac{1}{4} x^{2} =1\\\\ x^{2} =1: \frac{1}{4}=1*4=4\\\\x _{1} = \sqrt{4}=2\\\\x _{2}=- \sqrt{4}=-2\\\\\ \frac{4}{5} x^{2} -45=0\\\\ \frac{4}{5} x^{2} =45\\\\ x^{2} =45: \frac{4}{5}=45* \frac{5}{4}= \frac{225}{4} \\\\x _{1} = \sqrt{ \frac{225}{4} }= \frac{15}{2}=7,5\\\\x _{2} = - \sqrt{ \frac{225}{4} }=- \frac{15}{2}=-7,5\\\\\ x^{2}-16=0\\\\ x^{2} =16\\\\x _{1} = \sqrt{16}=4\\\\x _{2}=- \sqrt{16}=-4$