Algebra Trick to save you time (Algebra Tricks)

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Disclaimer: This video is for entertainment purposes only and should not be considered academic. Though all information is provided in good faith, no warranty of any kind, expressed or implied, is made with regards to the accuracy, validity, reliability, consistency, adequacy, or completeness of this information. Viewers should always verify the information provided in this video by consulting other reliable sources.

[BriTheMathGuy]

Make sure you only do this with LINEAR systems of equations.
AND check out my MATH TRICKS playlist!

[sunniiishxne]

Algebra, please stop asking us to find your X, she is never coming back and don’t ask Y

[itsmademo]

I took the risk on doing this technique in our Calculus exam, and it saved me a lot of time. I practiced your technique, sir. Afterwards, I used the same old process (Elimination-Subtitution) and yeah, I got the same answer.

[laylowxalex]

I really hate math because I feel like my future depends on it and if I dont pass I won't graduate it puts me a lot of pressure.

[buildthemansion]

During the pandemic I've decided to get into Math as a hobby. I've always wanted to just never had the time. This is an awesome trick. Thanks for sharing. Anybody have any suggestions. I'm building up to Physics.

[dari]

For anyone curious:

You can have this written down as Ax + By = C, and also Dx + Ey = F as the second equation.

If you isolate y in the first equation, you’ll end up with this equation: y = (C - Ax)/B

Now, if you plug that value of y in the second equation, you take these steps:

Dx + E[(C - Ax)/B] = F
Dx + (EC - EAx)/B = F
(DBx + EC - EAx)/B = F
DBx - EAx + EC = FB
(DB - EA)x + EC = FB
(DB - EA)x = FB - EC
x = (FB - EC)/(DB - EA)
x = (BF - EC)/(DB - AE)

And that’s exactly what’s done here

[avinashbabut.n]

In India, we are taught this like a formula.
This method is called the cross-multiplication method. The formula goes like this.
For the standard form of system of equations a1x + b1y + c1 = 0 and a2x + b2y + c2 = 0,
x/b1c2-b2c1 = y/c1a2-c2a1 = 1/a1b2-a2b1
This method is not exact to the method you said, but it is indeed similar...

[hosuecentro]

did he just solve an equation, backwards? wow

[redsoldier]

This guy...right here...is an absolute legend.Thanks alot for showing this method, I'll make sure I forward this to my friends and teachers!

[Mcbfggj]

Oh my gosh, thank you so so much. I am from Singapore and I’m secondary 2 or grade 8, the whole textbook was algebra, and you helped me so much, oh my gosh I can’t thank you enough!

[mathsguru]

This is called Cross multiplication method and very helpful when coefficients are small enough to multiply easily

[Golden_Tortoise]

This seems like more rules to memorize without understanding why it works. I dont think its worth memorizing this for such a small use case. I would rather do a tiny bit more work and be more confident in my answer. But cool trick nevertheless.

[chubbydawme]

Does he ever forget there's glass in front of him and he accidentally bumps his head on it

[micahsaldana]

I figured this out completely on my own when I was 18. I was going through my College Algebra book and was obsessed with finding shortcuts to solve things faster.

[sacoyacarter]

this is why i miss school i need to learn and virtial learning isnt helping me with math

[keo]

im crying you are so amazing, ever since grade 7 i have had terrible teachers so i struggled with basics and now i am in gr 11 and i have came so far with you videos .

[birajbbx]

We were taught this in elementary school, it's called CROSS MULTIPLICATION METHOD. We got 4 methods:-

1. Substitution method where we find the value of one variable and substitute it in the other equation.
2. Elimination method where we try to eliminate one of the variables by substracting, dividing, adding, or multiplying the equation. (My favorite)
3. Shifting method where we find the value of one particular variable (say x) from both the equation and then equate it with each other and solve for it.
4. Cross Multiplication method

The thing is that you just showed it directly but we had to do certain steps before that.
Nice Video BTW

[victorhernandez-egwp]

Wow I really enjoyed this video. I actually just finished linear algebra and solving systems of equations was a lot easier in matrix form. I wish I would have known about this back when I took algebra in high school. Love your videos. Keep up the good work.

[bernovanp]

Thank you so much Brian. Found this video last minute before my tests in Maths. It is very useful and I definetely subscribed. Thank you so much, Really appreciate it.

[dinkeshjain]

To tell this more simply this is the x/() =-y/() =1/() trick
In those brackets the coefficients of other than the variable you're writing it below.