Solving a quadratic by factoring | Quadratic equations | Algebra I | Khan Academy

[@jennymathews4292]

This was uploaded when I was two, now I’m a freshman. Crazy.

[@lali2955]

And now you're a sophomore.

[@Itsbilaa_55]

Hehe I think we're almost the same age

[@BasicRock123]

Crazy how these videos hold up 14 years later

[@jennymathews4292]

@@lali2955 Yep, crazy. I still think back to this doing Pre-Calc now lol

[@mask1776]

lol this was made 1 year before I was born

[@coolkid5850]

This video was uploaded when i was three now im a freshman

[@broganshirazi3706]

yo same except im a sophmore now

[@justyndeschenes7959]

Same

[@svian2]

@@broganshirazi3706 same

[@svian2]

Sophomore

[@turmoilbreaker9301]

how was grad?

[@mimilizzi97]

This video is way better than the other videos on this subject from Khan Academy. I watched the other videos about 4 times trying to understand the concept, before i found this one. As soon as i saw this one, I watched it, and understood it right away.

[@jadealex2190]

Thank you so much my teachers were making this so confusing for me but now I get it!

[@HybridBoarders]

This helped me out a lot i wish i found it sooner

[@KswolfVideos]

I've been trying to learn how to factor for several weeks. I just learned how in nine minutes.

[@maryjanesbaby9392]

Behold the Pale Horse Me too!

[@tbrew222]

Wow this video is so old... It was uploaded when I was in 3rd grade, and now I'm a sophomore

[@sarahkabir3683]

!! same here i was actually in the 2nd grade and its quite mind-blowing to think of it.

[@tbrew222]

*****​ lol ya I didn't even know he made videos back then

[@davidhovis2513]

Exactly the same lol

[@Rafakookoo]

Lol your comment was 4 years ago and I am now a sophomore, time flies!

[@geobrizuela]

SAME haha

[@neongalaxy9976]

This is older than me! And it’s teaching me lmao. Great video for people with bad teachers, like me

[@hotcopone]

hi thanks for the video. it really helps.. 1 thing tho. i recommend u should get those digital pen mouse things. its alot easier to write with and makes it alot clearer. thanks anyway... :)

[@YIJ_0]

This guy has been doing this before I was born, he needs a raise

[@kendallpressley3825]

This has helped me out so much, I wish I would have found it sooner!

[@noahjoo7231]

the quality of this video is just *chefs kiss*

[@mateomarangelli9191]

You want to know something sad? Last year, I was in Eighth Grade. I had Algebra 1 as the math course. (Because CPS does that now) My math teacher was awful. I learned absolutely nothing the whole year. You want to know something even sadder? This year, I am a freshman in High School. My math class is Honors Geometry 1. I received a High Pass on my algebra exit exam. I have no idea how. In H Geometry, we build off of stuff learned in A1. Stuff I didn't learn. I am screwed.

[@slavsquatsuperstar]

+Mateo Marangelli NOW WAY!

[@flyingmonkey2459]

+Mateo Marangelli story of my life

[@TrackieType]

+Mateo Marangelli Yeah, I'm in the middle of Eighth Grade right now. Teacher is horrible, I just learn the general topics and then just look up the actual subjects on Khan Academy. It is kind of sad, because I am recommended for AP Geometry next year.

[@CreatedbyLeon]

You're obviously good at math you just have to find someway to like the subject relate it to real life. Remember math is a skill, the more you do it the better you get at it.

[@CreatedbyLeon]

Reilitas true we get an overload of teachers who don't like their jobs or pay so they dont teach students anything. I'm currently in a catch up class at a CC and they put little to no effort in teaching the material mostly everything I learned I taught my self online or through books at stores. If I depended on the teachers I wouldn't pass.

[@soopi49]

Thanks very much Khan, this is really great and easy to follow.

[@lpoiuy341]

There is a book that only works with Algebra. I use this book while learning from this amazing teacher. It's called Effortless Algebra. This book shows step by step how to do algebra. I suggest to you all to get this book. It helps me a lot.

[@ChefKekeMartialArts]

Dang this video was made before i was born now im watching it because of math class in Grade 9 💀

[@celinebs]

great work my bro!!❤️ u just saved my grade

[@aksiadilet-sultan3321]

This video was uploaded a month before I was born and now it is saving my life as a freshman

[@Someone-gb8nf]

This video was uploaded when I was one month and 13 days old. I am a freshman now.

[@YdLeet]

Thanks ever so much Salman! :)

[@MovieMad007]

god if only I had this when i was at school I'd have been the top of the class!! Am 38 now and did my GCSE in summer of 86! The books that are around now like the "Dummies" series - eeesh I only wish I had these back then!

[@cool6936]

Awesome video, what i dont get though is that when you sketched the parabola the two x points would be positive however when you worked it out they were negative....

[@theforgottenbook7775]

You came down from heaven to help me study 😢

[@josejimenaz]

So much nostalgia at my college years

[@summeriswandering628]

wow i was 2 when this was uploaded and now i’m almost a senior.

[@AsEOfSp8dES14]

bluemicrowave is right, the parabola is on the wring side of the y-axis but that wasnt bad for an estimate

[@ronjansenmenor8147]

thank you khan academy learning has been so easy, and easy to watch because it only 240P but still readable and so fast to load

[@KeyurKumbhare]

notes2revise.blogspot.in/2017/03/algebra-khan-academy-notes-coming-soon.html

[@camcam1690]

this was uploaded a couple months after i was born, now im freshman

[@SamRobertduty]

Thank you !

[@runeslayerisawsome]

MATH PAPA

[@MCPhantomX]

lol it wants me to pay money now...

[@jameslee-vj9ez]

the parabola intersects the x axis at 2 and 4. when it should intersect it at -2 and -4. he graphed it first.

[@themanunderurbed]

Thanks this helps so much!

[@WhatTheShizzzzz]

better than my teacher

[@venkats1630]

Can u do a series of videos on parabolas because they seem a little confusing to me

[@HuntersWar]

Helped alot thx

[@234234234mr]

@bolmung that was just an example of what one looks like in the beginning.

[@Deathless2288]

it should be x = (-b +/- sqrt (b^2 - 4ac)) / 2a

[@GabrielEze]

Great video. You should also mention somewhere that solving a quadratic equation by factoring works only when the coefficient of x^2 is equals 1. That means when the coefficient of x^2 is NOT equals 1, and you're not able to divide across in a way that does not results in having a fraction anywhere in the equation, this method does not work. In that case, you will have to use the quadratic formula method or "completing the square" method. I know this is an old video, you could include this in the description section. Thanks for sharing

[@teaganmckay8706]

I feel like he did mention that when he divided 2x² by 2 in the second example problem. Although perhaps he could have put more emphasis on you having to do so for the problem to work.

[@angle4everr]

Can u plaese put up videos on factoring polynomails and ditstrubtive property.

[@airfreak789854521]

excellent job man! 100X better than my lame teacher and the textbook put together! xD

[@valdas0]

@RollsRoyceMr yes, his graph is wrong. Parabola should cross the x-axis at -2 and -4.

[@Sammyshots]

This video was uploaded when I was 4 months, now I'm a freshman

[@autumndockery441]

What if the two terms that we were factoring were not able to be evenly divided by two. How would you factor out once the big number was out of the way?

[@gasmaskguys4965]

very detailed (Y)

[@damarissamora8299]

This Was Made the year i was born now im in 8th grade

[@SaaditKhan]

@LancerZEV well, he took up the most of the 10 mins allowed, i dont see how he could have fit it in there, he's down a good job

[@lisinka3]

EDIT: It's supposed to be f(x) = -9^2 + 441

[@doctapeppamanjr]

Whoever said that the vertical line was the y-axis? It's obviously actually the line x = -6.

[@slavsquatsuperstar]

I was told never to divide, only factor out the 2

[@jinger1654]

I was a 3 months at this time lol

[@I0tnt4354g]

this video uploaded before I was born

[@sipsfactsandtea5535]

"nOw iM a SoPhMoRe" "nOw iM a FrEsHmEn" "i WaS tHrEe WhEn ThIs WaS pOsTeD" literally no one cares

[@Vortex-tl9xk]

h a

[@kieranarnold7525]

wow this video was uploaded when I was 6! now I'm unemployed

[@dimeemid7404]

It’s interesting to me to know stuff like that

[@rajeanam7976]

This video was made when I was four months old

[@nkolatsis]

His mistake I would think. -6 +5 = -1 which +6 -5 does not equal.

[@xKINGkhanSRKx]

you factored the 2 out at the starting, does that 2 just leave the equation now?

[@kikiscatto4826]

This video was uploaded when I was one I am a sophomore now

[@alyssaandalexis42]

Your zeros equal -2 and -4 but you graphed it on 2 and 4. Am I missing something?

[@alvifani]

Yes he did wrong in fact, by the Way not for purpose i guess. In the prospective OF the cartesian plane the parabola should have intersect the negative x axis

[@akerraahito7855]

how did you get -4 ?

[@NotTheBestPvP]

I'm wondering the same thing!

[@alvifani]

If u re talkin about the first problem, he found it as One OF the number u need the Make the equation equals zero. For instance : (x+4)=0, x must be equal -4 to satisfy the equation

[@NotTheBestPvP]

Thank you very much, didn't even realize that!

[@fivemeomedia]

i wish you could of explained what a parabola was first :/

[@gamerdio2503]

miguel look at a graph of X^2. That's a parabola

[@thejrespotlight.]

this was uploaded when I was -3

[@Raf-qz7ih]

i was -2

[@epbrennan0746]

I was -1 when this was uploaded. Now I’m in 8th grade

[@SaaditKhan]

@LancerZEV I didn't realize that missing one letter would cause you to "decipher" it... I think it's pretty obvious what I meant.

[@backlikevertabrae]

@dmiv424 So true, they always complicate things so much.

[@larrydeandixon8205]

this video was uploaded when i wasnt even a year old, now im a freshman

[@bolmung]

=( Was that parabola he drew in the beginning for the first problem just an example of what a parabola looks like? Because he got negative answers.... Would they have intersected the x axis on the negative side? Or am I not getting something? >.

[@BlancoPushP]

This was uploaded when I was 2 now I’m a sophomore

[@basalduat]

x= -4 and x= -2 is correct but your drawing shows that x=2 and x =4 ???

[@BenDurham]

No, not idiot, he probably didn't think of it... But yeah, just where ear buds or head sets... etc...

[@gracegilbert1666]

This video was uploaded when I was two months old and now I’m a sophomore

[@idster7]

is there any way to get the answers algebraically starting with A+B=-1 and AxB=-30??

[@baby-beetle]

this video was made when i was -4, now im 14

[@morenojader]

okay if X=-2 and X=-4 why the parabola is on the right side???

[@domigonz7094]

This video was uploaded when I was 1, now I'm a sophomore.

[@whodi2761]

ThIS ViDEo WaS UpLoAdEd WhEN I WaS 2

[@ahmedhasan3136]

why is fx equal to zero when parabola intersects x_axis at two points??

[@bakedseal3369]

cuz it is

[@ahmedhasan3136]

+BakedSeal ??!

[@pgbrandon]

f(x) is really the same thing as "y". What is the equation of the x-axis? y=0. Thus, setting y=0 gives you the zeroes or x-intercepts.

[@KeyurKumbhare]

notes2revise.blogspot.in/2017/03/algebra-khan-academy-notes-coming-soon.html

[@skittlegamingpg4145]

do you think next time you could make the audio a little bit lower

[@DeptBookDave]

I'm sure this is going to sound extremely foolish, but does anyone know any way to factor a quadratic with a 1 as the constant? Its status as the only single-factor number seems to mess up this process.

[@SaaditKhan]

@LancerZEV wooow, sorry I didn't know that you were the grammar police

[@printing11]

hes speaking fine....

[@tacocow6122]

If we can’t see air can fish see water

[@jerfersonmatos28]

Tacocow they can see even in the darkness

[@govamurali2309]

Why do we set f(x) as zero??

[@Nick-qc7wm]

i was 3 months old when this was made lol.

[@jinger1654]

Samee

[@lisinka3]

At your website, in the solving a quadratic by factoring module it spit out a problem of the type. f(x)=-9x2+441 I can't find how you would solve this in the video, and it doesn't give a hint. Can somebody help me out? (Answer is supposed to be x=7,7)

[@SaaditKhan]

@LancerZEV wooow, sorry, I didn't know that you were the grammar.

[@mrhnm]

When i factored it I got (2x+10)(x+5) can that work?

[@zoomyracecar7849]

When I multiplied it I got the starting equation so it should be acceptable

[@kaylad2663]

I was 3 when this was uploaded

[@shootingstars2127]

so wait can there be no x intercepts on a parabolic graph

[@joshavery]

What if there is no c term

[@sxcrekt6437]

It is 0

[@lukemcgregor6349]

This was uploaded when i was not alive now im, a 7th grader lol

[@DeptBookDave]

Nevermind. Just noticed that my equation had a coeffecient on the x^2 term. Sorry for wasting comment space with my oversight.

[@XxDem0nicG4merxXPro]

You mess up on the; when you divide the two your suppose to set Parethesies

[@tillienya3337]

this video is oldddd, I was a couple of months, not I'm in my later years of middle school

[@quantumhornet211]

TillieNya Dang same

[@dansingcow5129]

this was uploaded when i was 2 now im in gr 11 lmao

[@tjnstoptens3690]

Woah, i'm 12 now and i'm watching this like 8 years after

[@Glamerth]

119,820 Views......8 dislikes. HECK YES. =D

[@wonton55923]

but how do you foil?

[@nughson9868]

This video was made 8 months after I was born...

[@jerfersonmatos28]

Equação do segundo grau?

[@RollsRoyceMr]

the zeros are -2, -4 but your graph is showing 2, 4 or is it your concept of cartesian plane that is wrong ?!?!

[@thekmonkey101]

What if "C" is zero? :(

[@vadimasPK]

im using discriminant formula its more simpler