/sci/ - Science & Math

bump.

>>9612214
If you look closely there's a solution and explanation right below the question. Hope this helps!

>>9612249
I know, but I wanted to try it out with trig substitution and it didn’t work out. I don’t want to know the solution, I want to know why trig sub doesn’t work

>>9612214
And what trig substitution are you going to use for that?

>>9612261
>I have this Phillips head screw and the right screwdriver right here, but I really want to use a wrench. Why won't it work?

>>9612263
square root x = tan^2 (theta)

>>9612267
You can get answers with more than one method. That's not a very good analogy.

>>9612298
Ur implying math is consistent

>>9612298
it's not in the right form to use a trig sub. now go post this on /wsr/ or something. one calc II problem isn't really worth a thread

>>9612327
OP here. I just checked and trig sub does work. It gives you a different function, but the resulting graph is the same in both cases.

>>9612330
I got this result for your sub:
[math] \sqrt{x}= \tan^2 \theta[/math]
gives you the integral of
[math] \sin^3 \theta \cos \theta~d \theta[/math]

>>9612357
thats the problem, at this point you have to use a u-sub anyway, so why not just use it to begin with instead of a trig sub

just a demonstration of what Grandpa used to say:
>there is more than one way to skin a cat

>>9612357
OP here. That's what I got. The final answer is sin^4 (theta)

>>9612364
It probably sounds weird, but its easier for me this way

>>9612459
>The final answer is sin^4 (theta)
That's not the final answer though. How do you intend to bring this back into terms of [math]x[/math]?

>>9612479
x/((1 + sqrtx)^2)?

>>9612485
You're saying [math] \int \frac{dx}{(1+\sqrt x)^3} = \sin^4 \theta[/math]. Your final answer shouldn't be in terms of [math] \theta [/math] when the question is in terms of [math]x[/math].

>>9612492
I know, I phrased it wrong. My bad.

>>9612214
why the fuck would you simplify with trig?
just use x = u^2 to get it to be 2u/(1+u)^3, then add 0 = 2 - 2, getting (2u + 2)/(1+u)^3 - 2/(1+u)^3, which simplifies to 2/(1+u)^2 - 2/(1+u)^3. Then use the substitution u = w - 1 to get 2/w^2 - 2/w^3, from there, its absolutely basic
i have no idea why anybody would use trig on this problem

>>9612626

See: >>9612261

>>9612214
>It's not a homework problem because I SAID SO!
Fuck off, nigger.