a)
[tex]2 \times x \times x \times 8 = 125 \times 5[/tex]
[tex] \sqrt{2 \times 8 \times x \times x} = \sqrt{5 \times 125} [/tex]
|4×x|=25
[tex] = > 4x = 25 \: \: \: sau \: \: \: 4x = - 25[/tex]
[tex]x = \frac{25}{4} \: \: \: sau \: \: \: \: x = - \frac{25}{4} [/tex]
