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blackpenredpen
United States
Registrace 29. 12. 2012
I share the fun of solving math problems.
Check out my other channels "bprp calculus tutorials" or "bprp math basics" for math tutorials for your class.
Check out my other channels "bprp calculus tutorials" or "bprp math basics" for math tutorials for your class.
Solving a quartic equation by ABUSING the quadratic formula!
Try Brilliant with a 30-day free trial 👉 brilliant.org/blackpenredpen/ ( 20% off with this link!)
I created this quartic equation x^4-x^2-2x-1=0 and we will solve it by using the quadratic formula three times! Check out how we can factor x^4-x^2-2x-1 by using the double-cross method: czcams.com/video/kwZiaKytsSQ/video.html
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Big thanks to my Patrons for the full-marathon support!
Ben D, Grant S, Erik S. Mark M, Phillippe S. Michael Z, Nicole D. Camille E.
Nolan C. Jan P.
💪 Support this channel and get my math notes by becoming a patron: www.patreon.com/blackpenredpen
🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6
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#blackpenredpen #math #calculus #apcalculus
I created this quartic equation x^4-x^2-2x-1=0 and we will solve it by using the quadratic formula three times! Check out how we can factor x^4-x^2-2x-1 by using the double-cross method: czcams.com/video/kwZiaKytsSQ/video.html
----------------------------------------
Big thanks to my Patrons for the full-marathon support!
Ben D, Grant S, Erik S. Mark M, Phillippe S. Michael Z, Nicole D. Camille E.
Nolan C. Jan P.
💪 Support this channel and get my math notes by becoming a patron: www.patreon.com/blackpenredpen
🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6
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#blackpenredpen #math #calculus #apcalculus
zhlédnutí: 23 215
Video
Will the quadratic formula still work if a, b, c are not constants?
zhlédnutí 52KPřed 22 hodinami
I was driving back home and wondered if the quadratic formula still works if a, b, c are not constants? In fact, what if a, b, and c are functions of x? I created an incredible example based on this: czcams.com/video/j6ri-2S-hxU/video.html Newton's method (introduction & example) czcams.com/video/iVOsU4tnouk/video.html Big thanks to my Patrons for the full-marathon support! Ben D, Grant S, Erik...
I finally took the limit of the quadratic formula
zhlédnutí 62KPřed dnem
Math for fun! Taking the limit of the quadratic formula as a goes to infinity. Enjoy! Related videos: I differentiated the quadratic formula: czcams.com/video/JEcE-wDRMCk/video.htmlsi=b8kAyZmnWJpUcD1l I integrated the quadratic formula: czcams.com/video/J-p1tkaZKNg/video.htmlsi=tJfByRfw41NpP0JV Solve 0x^2 bx c=0 by @MichaelPennMath czcams.com/video/wTEYApUX-N8/video.htmlsi=NqbM6M_sElo2vj2J Big ...
You have seen the integral of ln(x) but might not be able to solve this problem
zhlédnutí 46KPřed 14 dny
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) I want the area under the curve y=ln(x) from 1 to some number t to be 2, but how can we achieve this? Not only do we have to use calculus integration by parts, but we also need to use the Lambert W function to solve the resulting equation for us. 💪 Support this channel and get my math no...
Oxford MAT asks: sin(72 degrees)
zhlédnutí 125KPřed měsícem
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) We will evaluate the exact value of sin(72 degrees) via the sin(5 theta) formula. This question is from the University of Oxford Math Admission Test in 2022 www.maths.ox.ac.uk/system/files/attachments/test22.pdf Big thanks to my Patrons for the full-marathon support! Ben D, Grant S, Erik...
Meet the 94-year-old calculus teacher! @ycmathematicsphysicsandche5659
zhlédnutí 22KPřed měsícem
Thanks to the CZcams algorithm, I discovered Mr. Feng, a 94-year-old calculus teacher, @ycmathematicsphysicsandche5659 . He said in his note that teaching makes him happy and makes his life meaningful, which I resonate with so much. I want to make a video to introduce him to you! Please consider subscribing to his channel and supporting what he does. Thank you. The solution to the derivative ch...
First time solving an A-Level maths exam! (90 minutes, uncut)
zhlédnutí 155KPřed měsícem
I will be doing a British A-Level further maths paper on the spot for the first time! This paper contains mainly algebra and calculus. Topics include complex numbers, hyperbolic equations, exponential equations, trigonometric identities and equations, first-order linear differential equations, determinant and the inverse of a 3x3 matrix, and more! Was I able to solve all the questions within 90...
How to solve the three-circle problem from the 2022 GCSE math exam
zhlédnutí 78KPřed měsícem
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) Here's the last question from the 2022 GCSE maths paper that made the news. We have three circles as shown and each radius is 4 cm. We have to find the area of the shaded region in the middle. I made a horrible mistake last time when I said the area of a circular sector is r*theta. The c...
Solutions to the 2023 AP Calc AB FRQ
zhlédnutí 32KPřed 2 měsíci
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) We will go over ALL the free response questions from the 2023 AP Calculus AB test to help you prepare for the upcoming AP exam. Topics included defined integral, average value of a function on an interval, change in position vs total distance traveled, implicit differentiation, related r...
You see nonlinear equations, they see linear algebra! (Harvard-MIT math tournament)
zhlédnutí 142KPřed 2 měsíci
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) This system of nonlinear equations is from the general round of the 2023 Harvard-MIT math tournament. www.hmmt.org/www/archive/271 I will present the linear algebra method I learned from their official solution to solve this system because I thought it was fascinating. It's from Harvard ...
Which is the worst math debate: 0^0, sqrt(1), 0.999...=1, or 12/3(4)?
zhlédnutí 271KPřed 3 měsíci
These are the most debated math topics on the Internet but which one is the worst? (A) 0 to the 0th power=1 or undefined. No calculus limit here. (B) sqrt(1) = 1 or both -1?) (C) 0.999...=1 or not? (D) order of operations 12/3(4)=1 or 16 More than 28,000 viewers voted in my recent poll and now let's discuss what each debate is all about. 🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6 💪 Get m...
You wouldn’t expect this "quadratic" equation to have 6 solutions!
zhlédnutí 122KPřed 3 měsíci
Surprisingly, the "quadratic" equation x^2 5abs(x)-6=0 has a total of 6 solutions (2 real and 4 complex solutions) which I did not expect. I came up with this equation purely by accident and I think it is super cool. It will feature complex numbers! 🛍 Shop my math t-shirt & hoodies: amzn.to/3qBeuw6 💪 Get my math notes by becoming a patron: www.patreon.com/blackpenredpen #blackpenredpen #math #c...
Using a logarithm property to make this equation easier!
zhlédnutí 90KPřed 3 měsíci
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) We will solve this power equation x^ln(4) x^ln(10)=x^ln(25). However, the process of solving this equation would require making one side equal to 0 but factoring every term by x^ln(4), and I don't think the expressions will look that nice. So instead, we can use the log property that a^l...
My first calculus 3 limit on YouTube
zhlédnutí 91KPřed 3 měsíci
Get started with a 30-day free trial on Brilliant: 👉brilliant.org/blackpenredpen/ ( 20% off with this link!) This is my first video on a multi-variable limit that you will see in your Calculus 3 class. We will evaluate the limit of y/x as (x,y) goes to (0,0) but how do we take care of this? We do get 0/0 indeterminate form but can we use L'Hopital's rule? 0:00 Limit of y/x as (x,y) goes to (0,0...
Believe in geometry, not squaring both sides!
zhlédnutí 264KPřed 5 měsíci
Believe in geometry, not squaring both sides!
Solution of the transcendental equation a^x+bx+c=0
zhlédnutí 154KPřed 5 měsíci
Solution of the transcendental equation a^x bx c=0
My failed attempts to the integral of sqrt(sin^2(x))
zhlédnutí 111KPřed 6 měsíci
My failed attempts to the integral of sqrt(sin^2(x))
Calculus teacher vs L'Hopital's rule students
zhlédnutí 87KPřed 6 měsíci
Calculus teacher vs L'Hopital's rule students
combining rational exponents, but using calculus,
zhlédnutí 97KPřed 6 měsíci
combining rational exponents, but using calculus,
easy derivative but it took me 32 minutes
zhlédnutí 179KPřed 6 měsíci
easy derivative but it took me 32 minutes
I couldn't solve x^x^x=2, so I solved x^x^(x+1)=2 instead
zhlédnutí 126KPřed 7 měsíci
I couldn't solve x^x^x=2, so I solved x^x^(x 1)=2 instead
all solutions to 2^x-3x-1=0 (transcendental equation)
zhlédnutí 141KPřed 7 měsíci
all solutions to 2^x-3x-1=0 (transcendental equation)
finally 0^0 approaches 0 after 6 years!
zhlédnutí 454KPřed 7 měsíci
finally 0^0 approaches 0 after 6 years!
I want all trig functions in one integral!
zhlédnutí 650KPřed 8 měsíci
I want all trig functions in one integral!
Berkeley Math Tournament calculus tiebreaker
zhlédnutí 90KPřed 8 měsíci
Berkeley Math Tournament calculus tiebreaker
Zvi is a Hebrew Israeli name pronounced "tze vee"
That graph looks a bit like an inverted Dirac-delta, which is a sufficiently cursed concept that you should do a video!
Didn’t know we could solve it that way. You used Tonelli théorème but you didn’t say the name. Great work tho
Still no reply Ignore V good 👍🏼
Bro went from high school to college in 9hrs
Wait, but if a^2 = 1/4 then there should be 4 answers, no? Two real answer and two complex answers
It's really simple!
Can this result be obtained from root locus
Thanks l am from Ethiopia 🇪🇹
Looking forward to solve the integral of " e^(x³) dx "
3:45 shouldn’t it be x^2 - x + 1?
I presume quadratic formula lawyers still did not appear just to sue you
5:32:53 the fact that he still cared about his handwriting at that point...
Sir please make videos on sieve theory
Why cant you just make e^x e^e^x to make it solvable
Just a small doubt on my part. while we derive the quadratic formula, it is usually established that a is not zero(since it wouldn't be a quadratic if it was). However if a, b and c can be functions in x(How does this generalize to all functions? Piecewise functions too?) zero(or any root of a) can be a perfectly legible root for the equation but the denominator for the quadratic formula can become undefined. Eg. (x-2)*x^2 + x - 2. I am really curious about this idea, but I don't think we will be able to derive powerful conclusions without rigorously answering these questions. I highly enjoyed your video nonetheless. Thank You. DISCLAIMER : This is a repost of my comment on the previous video posted, but I am also putting this here because I believe it would be more likely that you read it here.
Just a small doubt on my part. while we derive the quadratic formula, it is usually established that a is not zero(since it wouldn't be a quadratic if it was). However if a, b and c can be functions in x(How does this generalize to all functions? Piecewise functions too?) zero(or any root of a) can be a perfectly legible root for the equation but the denominator for the quadratic formula can become undefined. Eg. (x-2)*x^2 + x - 2. I am really curious about this idea, but I don't think we will be able to derive powerful conclusions without rigorously answering these questions. I highly enjoyed your video nonetheless. Thank You.
Keralites were shocked at the intro sponsor, until we saw the logo😂
Delta = Epsilon/2 is also correct right?
I want to know why do you keep holding the Pokémon ball ?
I have a question Can all irrational numbers be found for their rational approximation values? Example e use Taylor series you can find rational approximation values of e Are number super irational can be exist ?
The 3rd blackboard was the biggest plot twist imo
For the 186 case, notice that after subtracting one the RHS divides the prime, so 185=5*37 must divide it. Neither 5 nor 37 works.
For the 186 case, notice that after subtracting one the RHS divides the prime, so it must be a divisor of 185=5*37. Neither of these work.
is 0.9 the height for the triangles? cause the domain never goes to 1
A. It is an indeterminate form B. Square root of a number is always +ve C. ≠1 since it is tending to 1- D. The answer is 16 as if it was (3×4) then it would be 1 but (4) stands for (1×4) which indicates 16 as the answer So I would say there is no scope for any debate in any of these
'It is an indeterminate form' Please read about what indeterminate forms are. Usually, 0^0 is defined as 1. 'Square root of a number is always +ve' The *principal* square root, that is. '≠1 since it is tending to 1-' This is obvious nonsense. 0.999... is a real number and not a sequence or a function to be able to tend to anything. 0.999... is exactly 1.
Imagine being asked the Primorial of a Googol and you don't know the prime numbers.
Just put x= omega(w) and boom.
Very neat and direct. For those interested in a simple way, using polar coords, ( and simple to understand) I suggest you refer to Prime Newtons' video- it is nice for beginners.😊
x^4-(x^2+2x+1) =x^4-(x+1)^2 =(x^2-(x+1))(x^2+(x+1)) =(x^2-x-1)(x^2+x+1) Perfect square trinomial and difference of squares. I wonder which quartic equations are solvable via your method.
before watching: convert to difference of two squares (x^2)^2 - (x+1)^2 then two quadratic factors [x^2 - x - 1][x^2 + x + 1] = 0 . Real roots are phi, Complex roots (-1+- iRoot3)/2
when you think of exponentiation as dimensions the 0th dimension either has something or nothing
太酷啦
Let me make something simple for you. People who are asking why is lim of Cos h is 1 and lim of Sine h is 1 ??? It' because when we have the h approaching 0(h is same as theta btw). At that time hypotenuse becomes closer and closer and closer to adjacent side. So Cosine h would be 1. And Sine h would be 1 also.
Using the fact that [f(D_x)^2 - 1] y = 0 => [f(D_x) +/- 1] y = 0, you can show that, given ' [b(D_x) / a(D_x)] y ' exists, the quadratic formula also holds for certain sorts of differential operators a, b, c. (Analytic functions evaluated at the d/dx should work.) Notably, this is _not_ useful in solving most DEs, as I am aware of no techniques for solving the sort of non-linear non-sense that is x*y = [ - b(D_x) +/- sqrt( b(D_x)^2 - 4a(D_x)c(D_x) ) / 2a(D_x) ] y Best I can see is that the value of a solution at x=0, after applying the Quadratic-Formula'd Operator, would be 0. It is nifty to be able to isolate the non-constant part of the coefficients of a (very particular) DE, I guess.
Can't we just substitute x^2 as t and then solve ?
Yeah 👍
UTTPs with childs be like
One way I like to derive the quartic equation is to split the reduced quartic into a difference of squares of the form (x^2+ax+b)^2 = c(x+d)^2. In order to solve for the coefficients in this equation, you need to solve a cubic 'determinant' equation. Of course in this case, the coefficients are trivial.
hyperreal numbers are a joke to you?
that first equation was so cool
Yes it works, you are doing algebraic manipulation In every step (1) to (2), you are actually saying (for every x, if x is a solution to (2), x is a solution to (1)), the "for every x" effectively fixes a,b,c. For example: a(x)x=b(x) to x=b(x)/a(x). You are saying " For every possible x, if x' (one of the possible values of x) makes x'=b(x')/a(x'), then x' will also make a(x')x'=b(x') " Given correct assumptions, you can also say the converse. In the quadratic formula, just make sure a(x)=/=0 and every step is equivalent, you won't lose any roots. This is just rarely useful, isolating x and bundling every other functions with x together with a square root is rarely useful when you want to solve actual answers. However, this is quite useful in finding a numerical answer, if the right side with a(x),b(x),c(x) is convex around the answer, you can iterate to it
in the first case we can divide by 6 if we also multiply the 4 in mod by 2
Ok, but what does it mean when it adds 2pi, its a different value after all
When solving for the Z values in the Lagrange resolvent shouldn’t the 2 at the bottom be a -2? Since a=-1 or am I just being stupid
An interesting application would be for finding roots for equations of the form ax^3+bx+c/x, doing the trick from this video, then multiplying by x and taking the square root for a final solution.
You can do dots to immediately factor it. You have x²+2x+1 - x⁴ → (x+1)² - x⁴ → ( x²+x+1)(-x²+x+1)
Where did you buy the euler on the wall?
Hmm...I don't know what that would mean, lol, to abuse the quadratic formula, but maybe one can rewrite it as x⁴- (x²+2x+1)=0 => x⁴- (x+1)²=0, so, the difference of two squares, that would be (x²-x-1)(x²+x+1)=0, etc...just set each factor equal to 0, regular quadratics, etc...hopefully I didn't make some silly mistake...