>today
>to intelligent two study
>pic related in exam
>easy as fuck
>got confused by INT(x-1)^-2
>1h30min trying the fucking problem with integ. methods and log shit
>5 min left
>I remembered the denominators method exist
>check answer online
>(x-1)^-1
>tfw there were another question left
>tfw I might get up to 6/10 because of this problem
R*E^(10^100)
Today
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>1h30min trying the fucking problem with integ. methods and log shit
Didn't even try a u sub? Or think about moving on to the next question?
Please tell me those polynomial are irreducible
Can group the denominator up and haul our -X^2 on the left. Too intellectual to do it fully tb.h
[math]\frac{2x^2+x+3}{x^3-x^2-x+1} = \frac{2x^2+x+3}{(x+1)(x-1)^2}\\
\frac{2x^2+x+3}{(x+1)(x-1)^2} = \frac{A_0}{x+1}+\frac{A_1}{x-1}+\frac{A_2}{(x-1)^2}\\
2x^2+x+3 = A_0(x-1)^2+A_1(x-1)(x+1)+A_2(x+1)\\
2x^2+x+3 = A_0(x-1)^2+A_1(x^2-1)+A_2(x+1)\\
\left\{ \begin{array}{ccc}
x=+1 & 2+1+3 = 2A_2 \\
x=-1 & 2-1+3 = 4A_0 \end{array} \right.\\
\left\{ \begin{array}{ccc}
x=+1 & 6 = 2A_2 \\
x=-1 & 4 = 4A_0 \end{array} \right.\\
\left\{ \begin{array}{ccc}
x=+1 & 3 = A_2 \\
x=-1 & 1 = A_0 \end{array} \right.\\
x=0 \hspace{4 mm} 0+0+3 = A_0 -A_1 + A_2\\
x=0 \hspace{4 mm} 3 = 1 -A_1 + 3\\
x=0 \hspace{4 mm} -1 = -A_1\\
x=0 \hspace{4 mm} A_1 = 1\\
\frac{2x^2+x+3}{(x+1)(x-1)^2} = \frac{1}{x+1}+\frac{1}{x-1}+\frac{3}{(x-1)^2}\\
\int \frac{1}{x+1}\,dx + \int \frac{1}{x-1}\,dx + \int \frac{3}{(x-1)^2}\,dx\\
ln(x+1) + ln(x-1) + \int \frac{3}{u^2}\,du ; \hspace{4 mm} u=x+1, dx=du\\
ln(x+1) + ln(x-1) + \frac{3}{u}\frac{1}{-1} + C\\
ln(x+1) + ln(x-1) - \frac{3}{x+1} + C\\
[/math]
>cubic
>irreducible
[math]u=x-1,dx=du\\
ln(|x^2-1|)-\frac{3}{x-1}+C[/math]
>tfw to intelligent two skip questions
Because most physics is dull
Did you do that first factorization by inspection? I totally missed that
Literally me.
I still feel a lot of anger tonight. How the fuck do I get rid of this inner screeching?
en.wikipedia.org
It really helps to quickly find the roots.
It was Inspection. Thanks for the Rational Root theorem.
in the first step doesn't the last fraction have to be A2x+A3 over (x-1)^2 because youre dividing by a nonlinear function?
Nope, that's only in the case of an irreducible quadratic. That is (x-1)(x-1)
>didn't study
>got question wrong
>angry
You should now know you aren't as smart as you thought.
Study.
partial fractions and basic trig substitutions are literally the only things I remember from calc 2
>>check answer online
what?
After the exam I checked the answer online.
But I had everythin good.
The only problem was a simple Int[(x-1)^-2]dx
Fucking hell. It was to easy two study tho.
You should just skip university its for dumb people, just go get a job already. What are you? A brainlet?
I know, but I think it's a smart decision to do it anyway. Call it a genius' intuition.
This.
Also applies to this entire board.
>Had nearly same question on my final.
>Breezed through it in 5 minutes.
Maybe you should have studied, little baby brainlet.
>having finals where you compute hard integrals
Disgusting. You will NEVER need to do this by hand again, fyi
>factorize denominator
>partial fractions
>easy as shit integrals
Literally 5 minutes.
If you have to study you are a brainlet.
I gave up on "solving" integrals when I took probability. Now I just take a pair of dice to every "calculus" class and that usually gives me the right answer if I just apply the Monte Carlo method and other actual useful properties of probability.
Wrong. Did you even check your work with wolfram?
Just subtract both sides