Recent content by clifftan

the question is ∫dx/ x^2*√(x^2-1) I use x=a sec ∅ x^2*√(x^2-1)= sec^2∅tan∅ x=sec ∅ dx= sec∅tan∅d∅ so it will become something like this ∫sec∅tan∅d∅/sec^2∅tan∅= ∫1/sec∅d∅=∫cos∅d∅ =sin∅+c But how can i change this sin in...

Thank you very much~~

the question is ∫ √(y^2-25)/y^3 dy.. I did found the answer which is 1/5 sec^-1(y/5)-sin2∅/20-∅/10 But mine tutorial answer is 1/5 sec^-1(y/5)- √(y^2-25)/2y^2+c i don't know how to convert the behind part sin2∅/20-∅/10 into √(y^2-25)/2y^2