Explicação passo-a-passo:
[tex]a)~~\log_x30=\log_x2.3.5=\log_x2+\log_x3+\log_x5=\fbox{$a+b+c$}[/tex]
[tex]b)~~\log_x12=\log_x2^2.3=\log_x2^2+\log_x3=2\log_x2+\log_x3=\fbox{$2a+b$}[/tex]
[tex]c)~~\log_x50=\log_x2.5^2=\log_x2+\log_x5^2=\log_x2+2\log_x5=\fbox{$a+2c$}[/tex]
