Answer:
Step-by-step explanation:
[tex]\int\limits^8_2 {\frac{1}{\sqrt{x^2+64} } } \, dx[/tex]
[tex]u= x/8 \rightarrow dx = 8 du[/tex]
[tex]x^2 = 64 u\rightarrow x^2+64 = 64 u^2 + 64 = 64 ( u^2 +1)[/tex]
[tex]\int\limits^1_{1/4} {\frac{1}{8\sqrt{u^2+1} } } \, 8du[/tex]
[tex]\int\limits^1_{1/4} {\frac{1}{\sqrt{u^2+1} } \, du[/tex]
[tex]=ln(\sqrt{u^2+1}+u|_{1/4} ^1[/tex]
