Thread: definite integration

The integral of [ 1 / t^3 * sqrt(t^2 - 1) ] from sqrt(2) to 2.
Can someone help me in getting the integral..

I tried u substitution but got stuck..

u = sqrt(t^2-1)
du/dt = (1/2)(sqrt(t^2-1)^-(1/2)
du = " " * dt

dV = t^3
v = t^4/4

Is this the right way? I get stuck after I rewrite it..

is there an easier way, thank you

Originally Posted by xfyz

The integral of [ 1 / t^3 * sqrt(t^2 - 1) ] from sqrt(2) to 2.
Can someone help me in getting the integral..

I tried u substitution but got stuck..

u = sqrt(t^2-1)
du/dt = (1/2)(sqrt(t^2-1)^-(1/2)
du = " " * dt

dV = t^3
v = t^4/4

Is this the right way? I get stuck after I rewrite it..

is there an easier way, thank you

how about trig substitution?

that's what i immediately thought of when i saw it. i'll try it the integration by parts way to see if i have any luck with it

Originally Posted by Jhevon

how about trig substitution?

that's what i immediately thought of when i saw it. i'll try it the integration by parts way to see if i have any luck with it

sorry could you explain where you're getting t= sec(-)? Is this an identity or something?

Originally Posted by xfyz

sorry could you explain where you're getting t= sec(-)? Is this an identity or something?

yes, it's from one of the formulas for "trigonometric substitution." it's in your text, you can look it up