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simple intregration confusion

guys it lloks simple but i been getting different answers to these intrgration problems! pl help

show that ∫(x²)÷(√(x^6-1)) = 1/3 arcosh x³+ c

∫(4x)÷(√(x²+9)) = 8 + In3

thanks

Reply 1

Hitonagashi

For the first, let x³= u
3x² dx = du

= ¹/₃∫¹/_{√(u² - 1)}
= ¹/₃arcosh u + c
= ¹/₃ arcosh x³+c

For the second...I get
u= x²
du = 2x dx

= ∫²/_{√(u + 9)}

v= u+9
du = dv
= ∫²/_√(v)
= 4√v
=4√(x² + 9)

Cant see how x was supposed to be eliminated in your answer...