We will have the folowing:
[tex]x^{3.2}=87[/tex]
First, we take 3.2 to it's fraction form, that is:
[tex]3.2=\frac{16}{5}[/tex]
So:
[tex]x^{\frac{16}{5}}=87\Rightarrow\ln (x^{\frac{16}{5}})=\ln (87)[/tex][tex]\Rightarrow\frac{16}{5}\ln (x)=\ln (87)\Rightarrow\ln (x)=\frac{5\ln (87)}{16}[/tex][tex]\Rightarrow e^{\ln (x)}=e^{(\frac{5\ln(87)}{16})}\Rightarrow x=e^{(\ln (87^{\frac{5}{16}})}[/tex][tex]\Rightarrow x=87^{\frac{5}{16}}[/tex]
