Solving Systems of Equation via Substitution

[ematjaye]

2x+y=7 3x+2y=7 this is easy one this copy this one 3x+2(2x+7)=7 3x+4x+14=7 combined like terms 7x+14=7 subtract both side with 14 7x+-7 x= -1

[Hansen48066]

@ematjaye

This is not correct. You need to substitute (-2x + 7) into the equation.

3x+2(-2x+7)=7

3x - 4x + 14 = 7

-x = -7

x = 7

y = -7

[The305Gamer]

ok wher did he get the negative 2 from

[SlovesG8]

OMG. Thank you sosososososososososososo much!!!!!!!!!!!??:D This seriously helped!!!! My algebra teacher is gonna be shocked that I got this!!!:))

[TeamRussianSambo]

what if it says 3x + 4y = -1

and 4x - 3y = 7?

[Jhedsonm]

2x+y=7

3x+2y=7

plz solve it i don't know to solve..

.

[TyrellR1]

{x+y=10

x-y+2

[silvertrumpet1000]

this helps... alot



[vball22sball21]

this is my problem & i dont know how to do it ?

2x+8y=1

x=2y

[MDKIRBY7]

i love you

[nodice100]

@MDKIRBY7 LMAO 

[Alexys1017]

what if you DON'T have a variable with a coefficient of 1... I haven't watched the whole video yet so I don't know if you explain it, but... yeah lol

[FireIsTheCIeanser]

We wanna work smarter,not harder.

NO! I don't want to work at all

[McKrillian]

Good Video! but may i recommend a camera stand ?

[23ISLIFE]

im confused

y=x-7

4x-7y=10

someone help???

[ahkoifish]

Soooo helpful! Thank you so much!

[shankful1]

wth is that squeeking noise in the background

[NinjaBunnii99]

Wow thanks I get it now :)

[warchife6]

Wow... The future teacher, all hail youtube!!!

[XOneEyeWillieX]

Thank you, when ever i don't get something I come here and your videos help me out a bunch, each time you explain it I always get it :)

[kevenator12]

@XOneEyeWillieX did we have homework for biology?

[XOneEyeWillieX]

@kevenator12 LOL wtf stalker and no

[kevenator12]

@XOneEyeWillieX lol im not a stalker i just looked at recent and saw your dumb ass like this video

[XOneEyeWillieX]

@kevenator12 darn youtube

[MrHappyShooter]

Thank you so much my teacher has 30+ students 4 are passing with Ds She blames us for not know or listening but i totally understood you and took notes :D. Teacher been trying to teach us this for 3 months i learned it in under 5 minutes

[siyome]

Thank you! This really helped me!

[mycatzcute]

was any1 else really REALLY distracted by that random background noise? what was that?

[bigshow9386]

I have a question... My work sheet says:

y=- 1/3x+5

y=4/3x

how do you find the substitue?

[michaelannuittseng]

my teacher just yells it at us for the whole class

[jjd721]

thank you so much! took a 50 min lesson for my teacher but 5 min 4 youtube. youtube ftw

[HansKJohnson]

Thanks!! I have my final for the tri tomorrow and i couldn't remember how to do this.

[Utinii]

Wow, thank you so much! This is extremely helpful. I've been sitting here trying to figure out how to substitute and this helped alot. thanks :D

[kali2314]

Thank you so much for your videos. If it wasn't for you I'd be failing my math class right now. You make it so easy to understand! Thanks!!!

[rosalesspeed]

thanks i learn a lot tank you may this help in any person !

[SilentOneCorajuda13]

Good example Hansen48066. Cleared up my confusion. Thanks and good job

[crazyshitface69]

Thanks this was really helpful

[xxCASHiExx]

Another great video. Well done Mr. Hansen

[0xxSparkzofHopexx0]

Thank you so much. :D

I was working on a review sheet and was completely blanking out on how to do this. :)

[blackflame217484]

i get it xD now maybe i wont fail meh test thank you

[blackflame217484]

i gets it now xD mabeh i wont fail my test now thank you

[DjSmoog324]

you explained what my teacher tried to explain in 2 class of 50 minutes in almost 5 minutes.

thank you.

[greg1445441]

This Is so hard!!!!!

[GetItRight222]

Easy stuff

[lindseyrenee38]

how do i decide which variable to use if every variable has a number in front of it?? PLEASE HELP SOON.

[KoreanPridez]

thanks so much~

but i don't understand one part.

from

-3= x+5y, how do you get

x=5y-3?

[maiya2011]

oh my gosh :0 thank you so much i was doing

X+3y=13

-3x+2y=27 i got y=6 which i thinks right but i got x=31 and i think i messed up please help?

[kensleykatieashley]

AHHHH you just made my life soooo much easier!! but i do have a question what if your problem is x=y y=3x-2 see the first part is messing me up because my teacher never said any thing about this kind of problem.

[powerfuldill]

omg thanks so much my test is tommorow about this now i tottally get it thanks

[xxxbrittnyxxx6]

can anyone help me solve a problem im stuck on

[ILoveMusic916]

i seriously wish my teacher could do this.

[RVCAndrew]

i wish my teacher did this

[Priyamx19]

My worksheet says:

y = x

y = -x + 2

And I don't know what to do because I don't know what to plug innn?

[Hansen48066]

since y = x, meaning y is interchangeable with x, replace y with the letter x into the 2nd equation:

x = -x + 2. Now, solve for x.

[lordlusta]

your a math god you may have helped me to get an A thanks bro. :D

[ForeverLove155]

Thanks sooo much! I understand it know. Thanks to you I wont fail my test tomorrrow!

[alectra82]

Thanks! That made it easy...easier

[johnmurphmurph]

THANK YOU! Exam TOmorrow, and this will help!

[locomoco453]

i hate algebra

[TheEssGeee]

@locomoco453 Ughh , me too . I'm in freshman and i got a 'C' average for algebra. This suckss !

[SidneyCrosbyMVP2009]

thanks dude awesome:D

[SkateMX196]

THANK YOU!!!!!!!!!!!!

[blondgirl623]

thank you! you saved my life.

[coffebeansde33]

dude you are so awesome thnxs

[8888skysong]

This is so useful if you miss a day of school and your teacher expects you to know this.

[mrkskull]

THANK YOU U ARE GOD! u have to move to hong kong and teach at HKIS Core C Algebra PLEASE

[mysupasmileyface]

thank you thank you thank you!!

[MrNomofos]

Thank you man your a blessing to children

[Bubishi9]

thx a bunch man i love how I lean more off of a stranger on a 5 minute video on youtube than I do in lesson after lesson in math keep on making algebra vids and god bless you

[EmoKoreKids]

soo much easier to understand this way XD

[KevinTheNoobie]

And it took my teacher 45 minutes to explain this.

YouTube is so much better than some teachers out there.

[TheKyleBagley]

@KevinTheNoobie I still dont get it :P

[joshdrock]

@KevinTheNoobie lucky your teacher explained this. my teacher showed us like 2 problems and went on with his own business.

[bobredding]

Thank you prof for the instruction.

[javogreen07]

aleluya!! you saved my ass

[beachpeachx3]

dude, you teach way better than my math teacher. thankyou so much haha.

[wiredog1984]

what if it looks like this -y=6-2X DO YOU DIVIDE -Y BY ALL

[smiller42]

No: -y = -1y, so divide all everything on both sides by -1. Another way to think of it is as follows: "If negative y equals 6-2x, then positive y equals -6 +2x." In other words, flip the sign of everything on both sides of the = sign.

M.C. Miller

[3moory95]

wow thanks man

i suck in math

you saved me

[miguelroid]

No words can explain the awesome way you helped me!! Thank-You So MUch!!!!

[ngs5150]

Oh, I get it now.

[XxPharaohAtemxX]

wow, this is really helpful, my math teacher sucks at explaining >=\ so thanks for taking the time to make the video :o!!

[Pubeasaurus]

your like, just you

good work

[fenderxstrat]

do you teach at a school? You are very good it really helped my grade on this test. I could always do it in my head but never explain it. Thanks so much.

[lilmccleaner]

Thanks,!!!!!!!!!!!!!!!!!!!!!

[tink98555]

YOUR A LIFE SAVER!!

[kingr33per]

dude THANK YOU i didnt understand this till now thnx brah you saved me from getting an f

[haloboy100000]

Thank you so much you were very helpfull my algerbra teacher taught me wrong. Thanks again

[aznFlipnerd95]

Thanks, I understood how to solve x and y. I just needed to know how to use substitution. Thank you.

[LeandriaB]

Thank you.

[ForeverFading212]

wait, i'm confused. Dont you have to add 15 to both sides to get the y by itself? whyd you subtract the two?

[Hansen48066]

you have to combine the like terms of y first.

[Hickgirlallison]

thank you so much.

you are much better than my algebra teacher.

[asasdfer]

omg dis vid jst save me from failing d corter

[chubytuby]

This is easy stuff you learn in grade 10 mathematics. Excellent lesson.

[MasterMind300]

10 grade mathematics wtf why did i learn this in 6th?

[1krcm]

yea wtf i learned this in 7th

[mysupasmileyface]

I'm in 7th grade and I'm learning this..?

[mrkskull]

me 2!

[nikki0394]

thank you...i accually learned something lol

[cheezwhizz]

You're a genius, man. This helped me a lot, thanks.

The Algebra 2 book I have is terrible. It gives you 2 examples then 50 equations, and the methods of solving these equations are often poorly explainedd.

[XxlonleyXxone]

How do you know whether to put the -5y before or after -3 (in the first part)

Like In:

x+5y=-3

How do you know whether it is:

x=-3-5y

OR

x=-5y-3

When switching to the other side of the equal sign does the number ALWAYS go infront of the other one?...how do you know where to place it?

Im confused

[Hansen48066]

Good question. It is generally good practice to put the variables in descending exponential powers. Thus, it would be better to use x = -5y -3. You probably never learned this, but this is the same as x = -5y^1 -3y^0. See how the exponents decrease is power from left to right? Generally, the constant numbers (no variables) go last. Does this help?

[Futureballer2009]

what is

2x - y =0

-7x + y = -5

[Hansen48066]

top equation, solve for y: y = 2x. Replace y into bottom equation. -7x + 2x = -5. Can you solve it from here?

[MoonFaeries]

That was such a BIG help thanks for posting this!!!

[juniorchickn]

i understand how ur doing this, but i am confused about what to do with the variables like this example i have;

x - y = - 7

x + y = 14

[Hansen48066]

well, you can solve the first equation for x.

x = -7 + y. Then substitute it into the x variable in the second equation. Thus, -7 + y + y = 14. Solve for y from here.

[juniorchickn]

alright i solved for y

and i got y = 21/2

now i need to find x

[Hansen48066]

Right, so you have x + 21/2 = 14. Subtract 21/2 (which is 10.5, right?) from both sides and you've got it!

[juniorchickn]

thanks man! :)

[Hansen48066]

If you re-arrange the bottom equation:

2x = 3y + 2 x = 5y + 10

replace 5y + 10 into the x.

2(5y + 10) = 3y + 2

Can you solve it from here?

[sonicsnicx1]

excuse me im having a problem with

2x=3y+2

5y+10=x can u help me plz

[Redkonvict]

shouldnt 5y be after -3 not b4?

[Hansen48066]

not really, although I could have written it as

x = -3 - 5y if I had desired. However, it's usually most logical to keep terms in decending order. x = -5y -3 can also be though of as:

x = -5y^1 - 3y^0

From this perspective, the terms are in order. Nice question.

[dweb71]

thank you! your video explains substitution very well. =]

[hans6212]

thanks that really helped

[punkfalcon]

lovely. you really helped me understand. ugh, my algebra teacher could use some pointers on how to teach from you.

[devinechin]

thanks alot man that helped alot with my homework

[tearsgrabber]

Wow!!tnx 4 this vid..it helped me so much...can u post the solving of graphing the linear equation???

[Hansen48066]

Are you referring to solving a linear system of equations by graphing? I have one of these on my channel.

[upload]

You deserve teacher of the year award, you teach better than teachers. Thanks Mr.Hansen!

[pnoyguitar]

I have hard time doing 3 unknowns and 3 equations. Solving for X,Y,Z terms. Does any1 here know where to find tutorital for that?

[gnomesatemykeyboard]

Thank you so much! I have the worst Algebra teacher in the whole world. He never explains a thing and when he does he makes it ultra complicated and basically tells my class that we're stupid if we don't understand right off. Everything I've been struggling with for the past week you just explained in a little over than four and a half minutes! (p.s. edwardfelix is right!)

[edwardfelix]

"whew" thanks for posting man! it helped a lot!

[KraziAzian]

o.o im in seventh grade and your doing this in college ...

[pnoyguitar]

it's a lot different in college....7th grade is basic...College have the weirdest equations

[garnettoc]

ty for help im in 8th grade and my teacher is hard to understand atleast this way i can pause and reply

[AndyRoddick969]

i went to a crap school. im doing this stuff in college. im kinda pissed i went into a pretty crappy highschool

[piwitron]

amen

[AndyRoddick969]

yea, im glad someone agrees

[edwardfelix]

hey it happens, i was an expelled student and I was sent to the smallest charter high school were teachers (mostly old people) didn't even explain their material very well. by the time i graduated i had to retake the math classes in college because of their crappy teaching! A huge waste of time but hey you learn a lot better taking college math classes than high school in my opinion.

[SalemFU]

...can I get a hallelujah? PSH I went to an OHIO school... O! H! Y!....er...wait? huh?

[AndyRoddick969]

same, went to Ohio. teachers cant explain stuff.

[Pinki1017]

Thnx so much! I'm in Algebra 1H this year and i struggled so much on figuring how to solve these equations! Now i understand it!

Do you have any videos of Solving Systems by Graphing? Thnx again! :*)

[ravensfan1111]

thanks so much wow i can finally do my friekin homework thx man i was so confused (10th grade Algebra 2)

[pastordisastor]

im doing this in 8th grand alg 1 :D thanx my teacher doesnt explain it well enough

[pastordisastor]

im doing this in 8th grand alg 1 :D thanx my teacher doesnt explain it well enough

[jab1107]

This really helped thank you so much for posting it! :)

[bmxmaster145]

This one didn't make sense how u didn't explain how u got -5y-3 out of nowhere

[ps3jp911]

your my hero

[Krazyisthebest]

what grade is this for??

[Hansen48066]

8th Grade Algebra, Could easily be 9th Grade algebra, too.

[Austwill0]

THANK YOU!

[Morgisakim]

I have no idea what you just did. I'm completly confused.

[bmxmaster145]

me too

[ohokjess]

thank you sooooo much.

this helped so much.

continue to post these,

and they will help me get an A++++ in algebra.:)

[Sarahmint]

Thank you YouTube. Thank you Hansen teacher

[tsoinmy]

YOU ARE A GOD!!! THNX SO MUCH!! CUZ OF U I GOT AN A+ on my Test!!

[DeadlyDevil666]

OMFG THANK YOU SO MUCH!!! THis helped me understand it better!

[texa5boi]

THANK U SO MUCH. this will help me on my test for mrs.colemn

[rangedkid]

ty so much this will help me on my test!

[Hansen48066]

I don't teach Algebra any more... I'll have some pre-algebra stuff up in the future. Thanks for your interest!

[Jolting24]

thnks his helped

[kutskust]

nice job

[Hansen48066]

You're Welcome! I hope to record many more of these next year!