In this video , I showed how to find the area between intersecting curves
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@punditgi5 ай бұрын
Prime Newtons has done it again! Bravo! 🎉😊
@JourneyThroughMath5 ай бұрын
Prevideo Prediction: If I am remembering my calculus correctly, you would take the integral from 0 to 1 of x^2-x^3 then add the integral from 1 to 2 of x^3-x^2.
@mikefochtman71645 ай бұрын
Well I noticed the intersection point and did two integrals the same way (x^3-x^2). When the first one turned out to be negative area, I just took the absolute value and added it to the second result. The key of course is as you said, recognizing there is such a point within the range.
@vitotozzi19725 ай бұрын
Excelent explain!!!! How always......
@Amoeby5 ай бұрын
Right off the bat I can say that this one can trick many people.
@m.h.64705 ай бұрын
Solution: Given, that x³ = x² in x = 1, the two curves intersect there. As such, you need to calculate the area between 0 and 1, as well as the area between 1 and 2. After that, you need to add the absolute values of both to get the desired area. Alternatively, you can analyze, which curve is the bigger in which section and multiply the integral of the flipped section by -1. The latter is relatively simple, as (1/a)³ = 1/a³ < 1/a² = (1/a)². Therefore x³ < x² for 0 < x < 1. It is flipped, so x³ > x², for 1 < x < 2. So the desired area is -1 times the integral of x³ - x² between 0 and 1, plus the integral of x³ - x² between 1 and 2. The base function of x³ - x² is x⁴/4 - x³/3 + c Therefore the area is: A = -1 * ((1⁴/4 - 1³/3) - (0⁴/4 - 0³/3)) + (2⁴/4 - 2³/3) - (1⁴/4 - 1³/3) A = -1 * (1/4 - 1/3) + (16/4 - 8/3) - (1/4 - 1/3) A = -1 * (3/12 - 4/12) + (12/3 - 8/3) - (3/12 - 4/12) A = -1 * (-1/12) + 4/3 - (-1/12) A = 1/12 + 16/12 + 1/12 A = 18/12 = 3/2
@jacobgoldman57805 ай бұрын
Nice explaination! The tempting incorrect answer of integral(from x=0 to x=2 of x^3-x^2) gives 4-8/3=4/3.
@manojitmaity78935 ай бұрын
I get this also
@kingbeauregard5 ай бұрын
I wonder if there's any way to set this up so the right answer comes out automatically, like maybe if you square and then square root the integrand. Of course, it would be helpful only if you're trying to get the area, which isn't normally the case when you do a definite integral. It's probably simpler just to use your brain and intelligently assess the integral, most of the time.
@gabobllama26355 ай бұрын
Square and square root is functionally the same as absolute value. We can just integrate the absolute value of the difference of the functions. This would make us treat it as piecewise but unless I'm wrong this should work for any such problem.
@lylereibling5 ай бұрын
take the absolute value of each integal keeping the limits in order
@nothingbutmathproofs71505 ай бұрын
If you take the absolute value, then you don't have to be concerned with keeping the limits in order. That is the exact reason why you are taking the absolute value of the integrals.
@Blazing-Knight5 ай бұрын
We had a similar question. It was to find the equation of the curve that bisects the area between y = 9x² and y = 16x². I'd say that was merely easy was us. But I want you to propose a unique solution to the question.
@nanamacapagal83425 ай бұрын
MY SOLUTION: If anything you'd expect that mystery function f(x) to be between 9x² and 16x² Now set up the integrals and equate: Int[f(t) - 9t² dt, (0, x)] = Int[16t² - f(t) dt, (0, x)] [F(t) - 3t³ + C, (0, x)] = [(16/3)t³ - F(t) + C, (0, x)] F(x) - 3x³ = (16/3)x³ - F(x) 2F(x) = (25/3)x³ F(x) = (25/6)x³ f(x) = (25/2)x² which should make intuitive sense because every point on that curve is exactly half way in between y = 9x² and y = 16x²
@Blazing-Knight5 ай бұрын
@@nanamacapagal8342 Great one 👌🏻👌🏻 Love your approach. I solved it a bit differently but the answer is definitely the correct one.
@nanamacapagal83425 ай бұрын
@@Blazing-Knight thanks, at least i know my inline integral notation is readable
@Blazing-Knight5 ай бұрын
@@nanamacapagal8342 😂😂
@renzalightning60085 ай бұрын
This reminds me of the ones where you have regions under the x axis, and the question asks for the area. alas the integral per se will not give you the right answer, you have to be careful with those :3
@SakshamMahajanB5 ай бұрын
For a jee aspirant its easy 😄
@googlechachu2ndid3705 ай бұрын
Those who stop learning, stop living...🥰🥰... hits anyone hardly.
@pizza87255 ай бұрын
If x³ was set on top you would get 4÷3(close but no there) and if x² was set on top then it would be -4÷3(very far from the answer)
@ronaldjensen29485 ай бұрын
6:37 o.O :)
@jamesharmon49945 ай бұрын
Near the end you had 2 + 4 - 1/2, then you had 2 - 1/2. What happened to the 4??
@matthiaspihusch5 ай бұрын
Theres a - before the 2
@Sigint1235 ай бұрын
¿? 4 - 2 = 2
@matthiaspihusch5 ай бұрын
-2+4=2
@jamesharmon49945 ай бұрын
@matthiaspihusch Thank you!
@JSSTyger5 ай бұрын
I refuse to let my answer be wrong! First find the intersection points to be x=0 and x=1. Now evaluate the definite integrals for both functions from 0 to 1. You get 1/4 and 1/3. The area between them is 4/12-3/12=1/12. Now evaluate the definite integrals from 1 to 2. You get 15/4 and 7/3. The difference is 45/12-28/12=17/12. The final answer is 1/12+17/12=18/12=1.5.
@nothingbutmathproofs71505 ай бұрын
Too much work. I take the easy way out by just finding when the two functions are equal, which is when x=0 and x=1. Then I compute |int (x^3-x^2)dx from 0 to 1| + |int (x^3-x^2)dx from 1 to 2|, bypassing all the work to see which function is on top and where it is on top.
@jumpman82825 ай бұрын
Alternatively, do 𝑥³ > 𝑥². 𝑥 = 0 is not a solution. We know that 𝑥² > 0, so dividing both sides by 𝑥² doesn't flip the inequality. So, 𝑥³ > 𝑥² ⇒ 𝑥 > 1
@lukaskamin7555 ай бұрын
@@jumpman8282 why is x=0 is Not a solution??? 0²=0³! As well as not a solution of what???? Of inequality? Than you forgot that you can't divide by a function that potentially can be zero, that's how you get incorrect answer, you can only factor out and check the sign of expression ( all transferred to the same side) actually as shiwn in the video, all other speculations/simplifications made out if laziness will potentially lead to a mistake
@jumpman82825 ай бұрын
@lukaskamin755: Yes, 0³ = 0², which means that 0³ is not greater than 0² and thereby 𝑥 = 0 does not solve the inequality 𝑥³ > 𝑥². I am well aware that dividing by 𝑥² might lose 𝑥 = 0 as a potential solution, which is why I checked whether or not 𝑥 = 0 is a solution before dividing by 𝑥². As I mentioned I also checked that 𝑥² is not negative (which it can't be for real values of 𝑥) and thereby I can divide by 𝑥² without any worry.