If among all other memory requirements you have to know the integrals of sec(x) and sec^3(x) in a test ... Where does memorizing trig integrals end? 😬 ... then I guess I fail his class too. 😢 Lucky for me I'm not in integral Calculus and have a long list of Integral cheat sheet trig formulas of CRC tables to avoid that problem on my job!! 😂
I used the sustitution sen^2(theta)=1/(x+2), obtaining: cosec(theta)=sqr(x+2) and cotan(theta)=sqr(x+1). My integral was: (2cosec(theta)-2cosec^3(theta)) I had a equivalent result: ln|sqr(x+2)-sqr(x+1)|+sqr((x+2)(x+1))
(x+1)/(x+2) = u^2 This substitution lead us to integrating rational function without any secants After substitution proposed by me integration by parts will simplify partial fraction decomposition
To be honest, I don’t know why am I continuing to learning integration math more… I think I’ve found it funny and interesting since my hight school. So, for last question in the video, we actually can get rid of absolute value inside the natural logarithm, cause inside we have a sum of two square roots, which is always greater than zero, so we don’t need absolute value. But… Is it a mistake to just leave it here?
The first thing i thought wheb i saw that integral was to immediately put x+1 = tan^2(u), then the top simplifies, the bottom turns to sec and simplifies, so youve got the integral of sin(u) * dx/du du
Wolfram Alpha gives a very different result. Looks like your result only works for x > -1, so only for the real numbers. If you want complex solution, your way doesn't work.
@@niloneto1608Yes, my friend. When you see a problem, think of never dividing by zero. X can approach -2 but never reaches it. X is real by definition.
The function is undefined at x = -2 and is 0 at x = -1, but x < -2 and -2 < x < -1 can be calculated. The results for x < -2 are complex numbers, but they are still possible. And according to Wolfram Alpha, the integral CAN be calculated, so that these values are included.
It's been a while since I've watched one of your videos also sorry I failed your class😅
If among all other memory requirements you have to know the integrals of sec(x) and sec^3(x) in a test ... Where does memorizing trig integrals end? 😬 ... then I guess I fail his class too. 😢 Lucky for me I'm not in integral Calculus and have a long list of Integral cheat sheet trig formulas of CRC tables to avoid that problem on my job!! 😂
This is very well explained! I'd love to see more integral problems like this.
Thanks Sir for excellent explanation and good handwriting. 😊
at the end, you can get rid of the absolute value on the natural log since the sum of square roots is always positive
Awesome explain, thank you teacher 💐💙
31/8/2024
SATURDAY
10:52 AM
Fantastic question...🎉🎉🎉.
Learn new methods...
What if you used hyperbolic sub?
Then you'd find the -ln|...| in the solution be replaced with -1/2 * arccosh(2x+3)
Bless you good man
Thank you teacher
I used the sustitution sen^2(theta)=1/(x+2), obtaining: cosec(theta)=sqr(x+2) and cotan(theta)=sqr(x+1). My integral was: (2cosec(theta)-2cosec^3(theta)) I had a equivalent result: ln|sqr(x+2)-sqr(x+1)|+sqr((x+2)(x+1))
Nice professor
When you arrive at sqrt(u^2 - 1) better use u = cosh(t), with t >0
(x+1)/(x+2) = u^2
This substitution lead us to integrating rational function without any secants
After substitution proposed by me integration by parts will simplify partial fraction decomposition
Yes, that works too. Answer looking slightly different.
Can we use the standard formula for √(x^2-a^2)?
To be honest, I don’t know why am I continuing to learning integration math more… I think I’ve found it funny and interesting since my hight school.
So, for last question in the video, we actually can get rid of absolute value inside the natural logarithm, cause inside we have a sum of two square roots, which is always greater than zero, so we don’t need absolute value. But… Is it a mistake to just leave it here?
I already memorized radical x^2 - a^2 formula😂 i had an ode exam yesterday
Nice. if we let ch t=u as 2nd substitution i find the resolution much easier.
sir, can you explain how can u^2-1 be sec theta?
The first thing i thought wheb i saw that integral was to immediately put x+1 = tan^2(u), then the top simplifies, the bottom turns to sec and simplifies, so youve got the integral of sin(u) * dx/du du
❤
As far as the plus/minus is concerned, couldnt you ha e factored it out as a constant and then your final answer is +_answer?
If Im not much mistaken you can drop the absolute value. Both square roots are greater than 0.
Double substitution and a pair of trig identities. Wow.
AMAZING
Sir I have sent you a derivative question in your mail, please solve that
The absolute value inside ln in the final answer is unnecessary.
Use x+1=t^2
Very easy question
Wolfram Alpha gives a very different result. Looks like your result only works for x > -1, so only for the real numbers. If you want complex solution, your way doesn't work.
Because the function itself is only defined for x>-2. And usually complexo numbers doesn't associate with integrals of a single variable function.
@@niloneto1608Yes, my friend.
When you see a problem, think of never dividing by zero.
X can approach -2 but never reaches it.
X is real by definition.
The function is undefined at x = -2 and is 0 at x = -1, but x < -2 and -2 < x < -1 can be calculated. The results for x < -2 are complex numbers, but they are still possible. And according to Wolfram Alpha, the integral CAN be calculated, so that these values are included.
whats sec