0;\\
4t^2-5t+1=0;\\
D=b^2-4ac=25-16=9=3^2; \\
t_{1}= \frac{-b-\sqrt{D}}{2a}= \frac{5-3}{8}= \frac{1}{4};\\
t_{2}= \frac{-b+\sqrt{D}}{2a}= \frac{5+3}{8}=1;\\
(\frac{9}{4} )^x= \frac{1}{4} \\
x=\varnoyhing;\\
(\frac{9}{4})^x=1 ==>x=0 " alt="16^x-5\cdot36^x+4\cdot81^x=0;\\
(4^x)^2-5\cdot4^x\cdot9^x+4\cdot(9^x)^2=0;|\div (4^x)^2 \\
4\cdot( (\frac{9}{4} )^x)^2-5(\frac{9}{4})^x+1=0;\\
(\frac{9}{4})^x=t>0;\\
4t^2-5t+1=0;\\
D=b^2-4ac=25-16=9=3^2; \\
t_{1}= \frac{-b-\sqrt{D}}{2a}= \frac{5-3}{8}= \frac{1}{4};\\
t_{2}= \frac{-b+\sqrt{D}}{2a}= \frac{5+3}{8}=1;\\
(\frac{9}{4} )^x= \frac{1}{4} \\
x=\varnoyhing;\\
(\frac{9}{4})^x=1 ==>x=0 " align="absmiddle" class="latex-formula">