Respuesta :
[tex]8=2x+4\ \ \ \ |-4\\\\2x=4\ \ \ |:2\\\\\boxed{x=2}[/tex]
[tex]64x=16x-1\ \ \ |-16x\\\\48x=-1\ \ \ |:48\\\\\boxed{x=-\dfrac{1}{48}}[/tex]
Other equations (from comments):
[tex] 2^{x+4}=8\\\\2^{x+4}=2^3\iff x+4=3\ \ \ |-4\\\\\boxed{x=-1}\\--------------------------\\64^x=16^{x-1}\\\\(2^6)^x=(2^4)^{x-1}\\\\2^{6x}=2^{4(x-1)}\iff6x=4(x-1)\\\\6x=4x-4\ \ \ |-4x\\\\2x=-4\ \ \ \ |:2\\\\\boxed{x=-2} [/tex]
Used:
[tex](a^n)^m=a^{n\cdot m}\\\\\text{distributive property:}\ a(b-c)=ab-ac[/tex]