307

A,

$13^x=26\ \ \ \ \ Log$
$Log13^x=\ \log26$
$x\cdot\log13=\log26$
$x=\frac{\log26}{\log13}=1,27...$

B,

$4^x=\ 2\ 300\ 000$

$x=\frac{\log\ 2\ 300\ 000}{\log\ 4}$
$=\ 10,56..$

C,

$10^x=154$

$x=\ \frac{\log154}{\log10}=2,18...$

D,

$9^x=-81$

$x=\frac{\log\left(-81\right)}{\log9}$ = Ei ratkaisua