I am 47 years old and I am almost crying in front of my screen because all teachers should be like you. I deeply regret all the bad teachers I have had during my time in school.
Yep couldn't agree more. I had good maths teachers up until halfway through High School and then I got an absolute shambles of a teacher who killed my interest in the subject.
not to be annoying or anything but in my school they taught us that the square root of a number can be positive or negative and the same for any even root so it can be true, plus example 2 could be wrong too
I wish I had this lesson in high school. I only learned in college, precalc specifically, that the square root of x^2 is actually the absolute value of x. And that also caused confusion over why sometimes you solve for x using a square root and it becomes equal to +- something. All of that would have been cleared up if I had this lesson. (at least, I assume that's what the next part will be since I haven't watched it yet).
I like how you put the brackets to avoid ambiguity but for eg: SqRt (5^2) = plus, minus 5 because essentially like your example it is SqRt (25). However if you take (SqRt 5)^2 that is SqRt5 *SqRt5 = +5? The negative 5 does it exist?
No it is not. Square root of 25 is only positive 5 as this lesson makes clear. Now if you have x^2 =25 then yes, you will get X = + or - 5, but that minus came from the x^2. It has nothing to do with the square root itself.
But I was thinking if u do the square root of 5 first how u gonna get your 5 back by squaring it? :) I think einstein was somewhat right when he says... u can do perfect things with maths when u shelve reality aside but once u take reality into account its maths which usually get aside. :) As I go into maths the more I realize maths no better than any other science or subject. It does lots of things by assumptions, approximation and various hacks even at fundamental level... when it defines its rules. So how could it be any better? :)
@@Caldermologist i is not defined as the square root of negative 1. The imaginary unit is defined such that i squared equals -1. For the ewuation x^2=-1 there are two solutions: i and negative i. If you take the square root of a real number, let's say 9, you get the positive answer, that's the definition of the square root with real numbers. But in the complex world you can't compare two numbers. You can't say that one is bigger or smaller than the other. That's why you mathematicians can't decide whether i or -i is the square root of -1, so they decided to define i such that i^2 = -1. I hope that this was somewhat clear xD
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A good teacher teaches you how to solve the X,
A great teacher also teaches you the y (why)
And a bad teacher divides by 0
True
Somebody better quote that!
"Have your pens down" *simultaneous clunk of pens being put down*
I cannot stop being grateful for this teacher's existence
Could your students really know how lucky they are? Love the lessons.
I doubt it. from what I hear they just don't care enough about maths.
@@betterfly7398 honestly, his students sound interested
my guy we are all his students
@@ezychillz6322 Fr fr
Parent of a Yr 9 Student. Cloning tech is of no use, if we cannot clone people like you. What an inspiration you are!!! Salute.
i wish he was my teacher for math.
I am 47 years old and I am almost crying in front of my screen because all teachers should be like you. I deeply regret all the bad teachers I have had during my time in school.
Yep couldn't agree more. I had good maths teachers up until halfway through High School and then I got an absolute shambles of a teacher who killed my interest in the subject.
at 4:05 some 12 year old kids are having a roasting battle
You could write the rule as √(±a)² = +a.
5 years later and it still helps so much.
You present and teach so well. Love lesson on whiteboards like this.
"what the dickens is going on here"
he makes math doable for me and helped me understand surds when my teachers didnt, very effective teaching!
Love this guy, he reminds me of my teacher I had for years, she's just like him explaining everything and what it all means
legend. i learnt a term of maths in a hour.
not to be annoying or anything but in my school they taught us that the square root of a number can be positive or negative and the same for any even root so it can be true, plus example 2 could be wrong too
Epiphany after epiphany with master Woo. Thankyou
Only 15 replies this guys the best teacher on youtube!
I wish I had this lesson in high school. I only learned in college, precalc specifically, that the square root of x^2 is actually the absolute value of x. And that also caused confusion over why sometimes you solve for x using a square root and it becomes equal to +- something. All of that would have been cleared up if I had this lesson. (at least, I assume that's what the next part will be since I haven't watched it yet).
Such a good teacher. Teaches why and how. And he's so cute!!
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I like how you put the brackets to avoid ambiguity but for eg: SqRt (5^2) = plus, minus 5 because essentially like your example it is SqRt (25). However if you take (SqRt 5)^2 that is SqRt5 *SqRt5 = +5? The negative 5 does it exist?
Wonderful, youve helped me so much
Thanks for this video you’ve really helped me
I wish I could have this guy as a maths teacher
Shoutout to the Domain Of Science's mathematic's poster
Epic Math teacher, wish my teacher could teach
Wow!
Trying to teach myself about surds. Now I'm hearing about perfect squaring from photo math rip 💀
Nvm thought for a second now I figured about why xd
The square root of 25 is plus and minus 5
Its plus OR minus 5.
@@maxwell8866 ya, that’s what i meant
Except it's not
It's just 5
11:22 Could you write that as sqrt(x^2) = abs(x)??
I get that sqrt(5)^2 = 5 and sqrt(5^2) = 5 , so are they really different?
Enlightening video. Good job, Sir
Awesome explanation. Thank you!
I was learning this in Year 7. Mainly because I was very ahead in my class back then.
Mr Woo, which textbook are you teaching from?
is this malaysia maths 🌞
@@bencyber8595 Malaysian parents but Mr Woo was born in Australia.
Thank you :)
what is surds
tnx
w video
I wish I was in his Class
I don't like that illuminated eye below the chalkboard 😏😏
watching this in 2020 and every time i hear a cough being like carona
ps I make videos
Subscribed.
Ps. I also make videos but it's boring 😂
Aww thanks just subscribed to u too! :)
Square root 25 is positive and negative 5
Yes, in principle. However, square root is defined to be only the positive.
@@okaro6595. No it isn't. Its positive OR negative!
It's OR not AND I.e. plus or minus 5.
No it is not. Square root of 25 is only positive 5 as this lesson makes clear. Now if you have x^2 =25 then yes, you will get X = + or - 5, but that minus came from the x^2. It has nothing to do with the square root itself.
But I was thinking if u do the square root of 5 first how u gonna get your 5 back by squaring it? :)
I think einstein was somewhat right when he says... u can do perfect things with maths when u shelve reality aside but once u take reality into account its maths which usually get aside. :)
As I go into maths the more I realize maths no better than any other science or subject. It does lots of things by assumptions, approximation and various hacks even at fundamental level... when it defines its rules. So how could it be any better? :)
Can we say (+/-x^2)^1/2=x ??
AbdelRahman El-tawil you can't take the square root of negative numbers.
@@SeeTv. Of course you can. That is just one case where we need look at the calculation as being one done on complex numbers.
@@Caldermologist i is not defined as the square root of negative 1. The imaginary unit is defined such that i squared equals -1. For the ewuation x^2=-1 there are two solutions: i and negative i. If you take the square root of a real number, let's say 9, you get the positive answer, that's the definition of the square root with real numbers. But in the complex world you can't compare two numbers. You can't say that one is bigger or smaller than the other. That's why you mathematicians can't decide whether i or -i is the square root of -1, so they decided to define i such that i^2 = -1. I hope that this was somewhat clear xD
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Only 35 replies?
its 40 now