б) 4√1 - 5x = 2 ;

б) $$4√1 - 5x = 2$$.

$$4\sqrt[4]{1 - 5x} = 2 \implies \sqrt[4]{1 - 5x} = \frac{1}{2} \implies 1 - 5x = \frac{1}{16} \implies -5x = \frac{1}{16} - 1 = - \frac{15}{16} \implies x = \frac{3}{16}$$.

Ответ: $$\frac{3}{16}$$