x= \frac{9}{10}. \\2) 7^{5x}- 7^{5x-1}=6, 7* 7^{5x}- 7^{5x}=42, 7^5^x(7-1)=42, 7^5^x=7, \\ 5x=1=>x= \frac{1}{5} " alt="1) ( \frac{2}{3})^ \frac{x-1}{2}= \sqrt[20]{ \frac{3}{2} }, (( \frac{3}{2})^-^1)^ \frac{x-1}{2}, \frac{1-x}{2}= \frac{1}{20}, 1-x= \frac{1}{10}=>x= \frac{9}{10}. \\2) 7^{5x}- 7^{5x-1}=6, 7* 7^{5x}- 7^{5x}=42, 7^5^x(7-1)=42, 7^5^x=7, \\ 5x=1=>x= \frac{1}{5} " align="absmiddle" class="latex-formula">