kahn

$56^{3x-8}=1$ x=?

56^0 = 1

3x-8 = 0

3x = 8

x = 8/3

$3^{7-2x}={\left(\frac{1}{27}\right)}^{-8}$

x=?

$$\begin{array}{rl}& 3^{7-2x}={\left(\frac{1}{27}\right)}^{-8}\\ & 3^{7-2x}=3^{24}\\ & 7-2x=24\\ & 24-7=-2x\\ & \frac{17}{-2}=x\\ & x=-8.5\end{array}$$

$2^{3x+5}=64^{x-7}$

$$\begin{array}{rl}& 2^{3x+5}=64^{x-7}\\ & 2^{3x+5}=2^{6^x-7}\\ & 3x+5=6x-42\\ & 5+42=6x-3x\\ & 47=3x\\ & \frac{47}{3}=x\end{array}$$

$5^{x-12}={\left(\frac{1}{125}\right)}^{\frac{12}{5}}$

$$\begin{array}{rl}& 5^{x-12}={\left(\frac{1}{125}\right)}^{\frac{12}{5}}\\ & 5^{x-12}=5^{-3^{12/5}}\\ & x-12=-7.2\\ & x=-7.2+12\\ & x=4.8\end{array}$$