- 2(4x - 1) = ? ERROR ALERT! 75% of new algebra students make this mistake!

[@derekthemountaindawg467]

I've forgotten more than what the kids that are supposed to be learning this today know. These videos are a bit drawn out but very detailed and do refresh my memory. I remember when I used to ask when will i use this in real life and the distributive property is one that i don't think I've ever used.

[@lintelle2382]

I ain't staying around for twelve minutes to hear what all you got to say about this, but the answer is -8x+2.

[@Shimmering_rain]

That's what I got.

[@ralts6464]

ez

[@preparados1917]

We are not the target audience. I assume the target audience is people challenged in math.

[@franklinshouse8719]

I think the question would have made more sense if we had been asked to simplify rather than solve. I tried to solve for x, but that didn't work. The ? leaves it a little ambiguous. Are there 2 variables to solve for (x and ?). Or are we to solve for the ?.

[@rodbennett]

I agree. Maths is harder enough without this sort of thing. Simplify the expression or set the equation equal to something as the question.

[@rick420buzz]

-8x+2

[@marbymendez8021]

-2 (4X-1) = ? Simplify and expand the term -8X+2 Therefore -2(4X-1)=-8X+2 Identity

[@ronnieq9706]

I did get -8x+2... However, I then solved for x to get x=1/4. I see I should have stopped at -8x+2.

[@SpideyVids]

I did exactly the same - we were taught to finish maths problems in 1970s UK grammar schools.

[@francisdelpuech6415]

Me too

[@antmo1966]

Hey, you know why they use a different version of x when they mean the variable x... it's because x can also be used as the multiplication symbol. That to me looks like 4 times -1 inside the bracket.

[@evan752]

Multiplication is only represented by an "x" when you are teaching elementary aged children the concept of multiplication There is almost never a reason to write "4x3" instead of just putting "12" in algebra

[@priscacharo4718]

Qn: - 2 (4x -1)=? -8x+2=? -8x+2=0 Step 1> (take +2 the other side) -8x= - 2 Step 2> (solve x) -8x/-8x= - 2/ - 8x (-ve x - ve= +ve) or (-ve/-ve= +ve) x= 1/4 I can't believe I got it wrong😂 Aren't we to continue and solve X? You misled us Tr...you placed a? after the = 😅😬😅

[@wholehogfan]

@harplebluessolving for x is the name of the game in physics and more advanced math. So if you solve for x it’s 1/4. Now plug 1/4 in for x into the original problem. -2(1-1)=0 However I would agree that the equation he presented is incomplete or that you must assume -2(4x-1)=0 because it’s not otherwise noted. If it was = to 1 or 2 or 10^9123 it would have to be noted in the equation. Which in this case it was not. Now that’s not to say you can’t solve for -2(4x-1)=9^9123….you absolutely can and should be able to do in basic algebra

[@wholehogfan]

@harpleblues if you want to check your work and make sure it’s correct you need to solve for x.

[@eyelesspotato2189]

Your last comment (re: an experienced teacher seeing the commonn mistakes) made me think about my son's education. His math tests and quizzes are all administered (and scored) on a computer. I am not sure whether his teachers look at the responses, or just the total score that the computer gives them. Are you concerned about this (and the direction of the field) as an experienced teacher?

[@clarkgrayhame1250]

-2(×=-1/4) = 1/2 Wow I definitely need a refresher in algebra.

[@bobrobinson1399]

Ithink you should show an x differently to a multiplication signals I thought the equation was minus 2 brackets 4 times minus one brackets😢

[@TheloniousCube]

x is not commonly used for multiplication once you reach algebra - it is more commonly a variable. Multiplication is shown by placing terms adjacent to one another like "2(6-3)" which is (two times the quantity six minus three" or if necessary with * ad in "6*3" (six times three)

[@geneloscowski3070]

42 years, got you beat. My passion is advanced math, Theory of Probability and Combinations and Permutations.

[@geneloscowski3070]

@user-ky5dy5hl4d You obviously know nothing about the Theory of Probability or Combinations and Permutations!!!!! But to answer you first question, a point has no dimension!!! You must utilize Quantum math to solve Planck theory. However, you could use the Singleton theory and the Bernoulli process to align the possibilities in relationship to the c.

[@geneloscowski3070]

@user-ky5dy5hl4d I teach online courses. I suggest you pay the fees and join my courses. However, you have to have prerequisites before taking the courses. Algebre I, II and III, Calculus I, II and III, along with Algebric topology. Then I'll welcome into the class. I suggest you take the Theory of Probability first, then Combinations and Permutations.

[@geneloscowski3070]

Also, in reference to you question on dimensions! You must first, consider spactial homologic abstract points within a dimension.

[@geneloscowski3070]

@user-ky5dy5hl4d We now turn to analyzing the finite set of points, S, that approximate the compact set X in the metric space (M, d). As described in the introduction, we let ρ be the Hausdorff distance dH (X, S) = ρ. In this section, we show how to relate the inverse systems of -neighborhoods, (X, pλ) and (S, qλ), and derive bounds on the persistent Betti numbers of X. Since X ⊂ Sρ and S ⊂ Xρ, we have the following inclusion maps for any  > 0, i : S → X+ρ and j : X → S+ρ. With appropriate bonding morphisms, this gives us a commuting diagram for any λ ≥ ρ and  ≥ λ + 2ρ: Xλ Xε SSSS λ−ρ λ+ρ ε−ρ ε+ρ (11) This diagram implies that if an element of Hk(X) has a preimage in Hk(Xλ), there must be an element of Hk(S−ρ) with a preimage in Hk(Sλ+ρ). Similarly, if S+ρ has a hole that persists in Sλ−ρ, there must be a corresponding hole in X that persists in Xλ. In terms of Betti numbers, we have that for λ ≥ ρ and  ≥ λ + 2ρ, βλ−ρ k (S+ρ) ≤ βλ k (X) ≤ βλ+ρ k (S−ρ). (12

[@daithi1966]

Why would you stop at -8x + 2? My answer would have been x = 1/4

[@LA610]

confused....why don't you solve for x....1/4

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@WilliamRoe-nz6qc]

Watched this and still dont understand Algebra. What is the significance of the "x"? My brain always wants to try multiplying the number with the x but x has no value. Weird is Algebra. I have always been very poor at any sort of Maths but ok on basic arithmetic.

[@artwright3128]

.25

[@dioniciotorres4290]

You use the "dioniçio" or distributive law

[@paulroscoe264]

how do you know it was 4x and not 4 ‘multiplied’ by minus 1?

[@pammuir5364]

X=1/4

[@mikemidulster]

How do you find the value of 'x'?

[@robertmagnier953]

You don’t , see where the equal sign is?,,look on this as one side of a normal equation.

[@marymurphy937]

--8x = --2 8x = 2 divide both sides by 8 x = 2÷8 x. =2/8. ( divide above and below by 2) x. = 1/4 ( I.e one quarter)

[@Deploracle]

@@marymurphy937 Actually the answer isn't a number, it's a function of ?. x = (? - 2) / -8 The mistake is moving the 2 to the right side of the equation -8x+2=? and your mind inserted a "0" in place of the ?.

[@TheloniousCube]

@@marymurphy937 No, you don't have a zero on the right side, just a '?'

[@TheloniousCube]

You don't - that's not the question

[@pammuir5364]

Don’t you continue and solve for x?

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@ApiaryManager]

-8X+2 It isn't anerror. It's a mistake.

[@robduijf2752]

2/8 => 1/4

[@troyallen8223]

Halfway through... What happened to PEMDAS? Please explain

[@mikekenyon3322]

other than a mental exercise, how is this used in real adult life?

[@mbeards5323]

Distributive property was used here.

[@sylviasmith2510]

You always work inside the bracket first Answer is -2

[@curtriceennis2924]

@AstridinGeorgia This is how I came up with a positive answer. ... - 2 (4x - 1) = -8 x + 2 = - 8 x = - 2 X = - 2/- 8 X = 1/4 - 8 x = - 2 -8(1/4) = -2 -8/4 = -2 If it was -8( - 1/4) = - 2 That would work out to be 2 = - 2

[@TheloniousCube]

You can't do line 3 because you do not know there is a zero on the right This is not an equation to solve for x

[@AstridinGeorgia]

You don't subtract 2 from both sides after getting that?

[@curtriceennis2924]

That's what I was wondering, too. So, I solved for "X" and came out with "X = - 1/4."

[@AstridinGeorgia]

@@curtriceennis2924 Me too.

[@vespa2860]

Ok, I'll bite. What are you referring to?

[@curtriceennis2924]

@@vespa2860 @vespa2860 DK exactly how to explain it, but, it's an operation in algebra where you solve an equation using the "Properties Of Equality" method. If you will Google the POE method, it may direct you to a site that can explain exactly what that method is. I can tell you how it's a method they at least USED to teach in Algebra a long time ago. But, things change over the years, and, I don't know if they still teach that method. 😉

[@curtriceennis2924]

@@AstridinGeorgia Believe it's supposed to be a positive fraction of 1/4 instead of negative.

[@domenikahila8585]

-8x +2 ×= 8+2 ×=10

[@wadepittenger5661]

The answer is 42.

[@markboyce1001]

I got that one wrong,but seen my error, thanks for that.

[@wellspj2002]

What would the answer be if you solved for X......if that is a correct question

[@Deploracle]

X = ( ? - 2 ) / -8

[@TheloniousCube]

You can't really solve for x (unless you treat '?' as a variable) - the goal is to simplify the expression

[@TheloniousCube]

@@Deploracle '?' is not a variable

[@Deploracle]

@@TheloniousCube Sure it is.

[@TheloniousCube]

@@Deploracle No, in this instance it's punctuation - the question is about simplifying terms, not solving equations

[@fayeeisener4359]

Shouldn’t the goal be to solve for x?

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@anitawallace2166]

I haven’t had a math class in 50 years. I know I learned about negative numbers but I have no memory at all of how to multiply or divide with them . And I don’t remember anything about logs. Sigh.

[@HeiseWurgl]

Oh yeah! at 1:35 you say you have graded in many, many, many years 10.000.000 quizes (or whatever). Oh yeah! So lets say this "many, many, many" is 35 years and a year has 365.24 days. This means that every day you did ~780 quizes (or whatever). No weekend, no holiday, no vacation. Oh yeah!

[@candyraborn812]

4

[@stevenjohnson1143]

-8x+2 easy

[@michaelvessels9668]

8

[@wijnenzo8822]

8? Or minus 8 not sur anymore

[@KenFullman]

Multiply the -2 by both parts inside the brackets and you get -8x and +2 so put these together and you get 2-8x I'll resume the video now to see if I made the common mistake.

[@KenFullman]

Yay. Got it! But I'm not immune to mistakes so I'm going to call this one a win.

[@Shimmering_rain]

Also can be written as -8x+2. I prefer this way for several reasons.

[@jonmc6573]

you get -8x and +2 so put these together and you get -8x+2... you inverted the formula.

[@KenFullman]

@@jonmc6573 It's exactly the same. -8x and +2 It doesn't matter which way around you put them. I just prefer having the positive one first. It just feels more natural.

[@jonmc6573]

@@KenFullman I didn't say it was different. I said you reversed the formula. You might find it looks better but it is a pointless and confusing exercise to most people.

[@conken9615]

You didn't explain why u didn't do pemba. Should be in ( ).

[@conken9615]

Why isn't it 4x-1=(3x)

[@TheloniousCube]

@@conken9615 Because 4x-1 does not equal 3x

[@troyallen8223]

That looks like minus one not negative one

[@TheloniousCube]

Same thing

[@darrylsmith-oy7vp]

Bro, I'm new to cellular stuff. No not good AT ALL 🥺 Tech Culture has left me Far Behind and truth told I'M FEARFUL OF IT AND A.I.🤐 just recently found ur channel on you tude. Trying not to download harmful ☢️ sites. Allow my grands to come and evaluate and further assist with the process. Again, thnks

[@winstonsmyth1646]

The answer is -2

[@darrylsmith-oy7vp]

Bro, u have me soo! Excited 👍 I just had a love affair with math in both highschool and college. Although, I struggled in college. I was thirsty for math challenges. I have forgotten the rules to do fractions! Use to solve such problems in my head😊 That calculus had me up many late nites. I only passed because final exam was mainly the homework problems. No, never had the concept of volume relations as u explained it. Area sound familiar? The professor explain summation @ V knot (0) and demand that u show the work! Not the right answer which was given on most test n quizzes. Also, lots of paper needed for 1 #. Test were done on butcher paper? yeah, a long sheet!Thanks I sub on occasions and the highschool is always desperate to cover math classes! Well, I always say no, mainly because of calculators usage by the students, which is not learning, in my opinion. But I just might put my name on the available list!🤔 And take s Crash Course @ using a calculator for advanced mathematics.

[@leetrask6042]

I got 2-8x

[@gardenersdelight7479]

What the heck! This is why I switch off with equations like this. Why does the subtract sign get changed to a negative sign? It was 4x minus 1. Makes no sense. How would anyone know to do that. It’s not logical in any way. At least for my brain it’s not logical. And why for no reason if you can choose to change a minus to a plus, then what’s to not stop anyone deciding to switch a divide out for a multiply any time they fancy! 😂 If you follow it logically you would have to complete what’s in the parentheses first which would be 3x and the multiply it by negative 2 so the answer would be negative 6x. But no, the rule is broken and you are multiplying outside and inside. And where the f did the 3 come from? 🤯🤦🏻‍♀️🤷🏻‍♀️ ☠️

[@TheloniousCube]

Because subtraction is equivalent to adding a negative, that is to say x - 1 = x + (-1) and x-y = x+(-y). In algebra it's often best to make this substitution so you only have addition operations. It's perfectly logical. "what’s to not stop anyone deciding to switch a divide out for a multiply any time they fancy! " - The same can be done with multiplication and division where dividing by two is the same thing as multiplying by one half. So yes, you can swap multiplication for division whenever you like as long as you obey the rules. It really does all make sense once you truly understand how negative numbers and fractions work. "what’s in the parentheses first which would be 3x" - no, because you're not taking away an x, but rather a one. 4x-1 does not reduce or simplify because the two terms (4x and 1) are different.

[@melissahao]

1/16

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@MeBallerman]

-2(4x-1)=717

[@steelcommander5751]

bro whats x ?

[@MeBallerman]

@@steelcommander5751 That's hard to say.

[@marymurphy937]

Answer i/4.

[@mylittlepitbull3143]

154th comment

[@bjornbjornson9359]

You can not solve it

[@renatovonschumacher3511]

How glad I am for not having YOU as my Math teacher . .

[@maymei2805]

Agree! I am confused by listening to him.

[@vanessahuman7607]

0

[@steelcommander5751]

-8x+2 right ?

[@siral6733]

My awnser was 0

[@SeamyEmail]

waste of time

[@moreenvakaliwaliwa6775]

-8x +2

[@MsElaineLewis]

x=1/4

[@robertnewkirk245]

8

[@ronnieq9706]

x=1/4

[@danieldennis9831]

-8x+2

[@rickdoty3067]

-8x+2

[@beauchamp02]

8

[@danielmadden9691]

X= 1/4

[@Kat-ex8nl]

X=1/4

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@ernestgirard9457]

7

[@mirkozlikovski9553]

x = 1/4

[@TheloniousCube]

You cannot solve for x because the right-hand side is "?" - the question is about simplifying terms, not solving equations

[@mirkozlikovski9553]

@@TheloniousCube you're right! but... why is it written as an equation?!? then it would be better not to write it as an equation, but just simply say: "simplify the following expression"! written like this it's just like the "famous viral math problem"... an expression with ambiguous notation (the latter just for those unfamiliar with the way common exposed factors are written in front of the brackets).... so, I assumed in a first glance (and without clicking the video until you replied 😔) that the "equation" I see, equals to nothing and it has to be solved for x... my "hasty" bad!😒

[@TheloniousCube]

@@mirkozlikovski9553 It's written as an equation because a simplified expression is equal to the original expression. This is common practice in math and simply means "find a better expression that means the same thing." This should be clear to anyone who works with math on a regular basis - including students. I'm not sure which "viral math problem" you're discussing

[@mirkozlikovski9553]

@@TheloniousCube as I said.... you're right and I made a mistake out of inattention and haste! "the famous" one, 6 : 2(2 + 1).... that in "my version of old math" would result as 1, because of the convention that when you see the factor in front of the expression in brackets, without the multiplication sign between them, it means that it is a common exposed factor of the term in brackets and NOT a self standing term of the larger expression! for me to get 9, it should be written as 6 : 2 x (2 + 1) or, to be exact/not ambiguous for "any kind of math", it should be written completely as 6 : (2 x (2 + 1))

[@TheloniousCube]

@@mirkozlikovski9553 I have never heard of the "common exposed factor" notation