4 = 5 and 2*2 = 5 !!! come see!

[Nantuko_Husk]

I will prove to you that 4 = 5

so we got the initial form

16-36 = 25-45

16-36 + (81/4) = 25-45 + (81/4)

4² - 2 * 4 * (9/2) + (9/2)² = 5² - 2*5*(9/2) + (9/2)²

[4 - (9/2)]² = [5 - (9/2)]²

√{ [4 - (9/2)]² } = √{ [5 - (9/2)]² }

4 - 9/2 = 5 - 9/2

4 = 5

2*2 = 5

so...what do you say about this one?

 

[Raiju]

:shock:

 

[Daelin]

WRONG!

√{ [4 - (9/2)]² } = √{ [5 - (9/2)]² }

That's perfectly correct, I followed all the steps. However, when getting rid of the sqrt (rising the entire expression at power 2) you have both the expressions in modulo.

=> |[4-(9/2)]| = |5-(9/2)]|

And now, let's study the modulo function:

|x|=x, if x>=0 or (-x), if x<0.

=> |4-4.5|=|-0.5|=-(-0.5)=0.5
|5-4.5|=|0.5|=0.5

0.5=0.5 which is true!

Conclusion, your demonstration is false!

~Daelin

 

[Raiju]

guys im on vacation...i dont wanna even see math, this is giving nauseas...

 

[Nantuko_Husk]

well,dont be so sure.

the thing you are calling modulo is what i call absolute value,anyway...
I dont have any of these. i just put '{' and '[' characters to make the expression more understandable.

since it would have been like this

(4 - (9/2))² = (5 - (9/2))²

I just didnt want too much parenthesis.
I added the [ because i put 9/2 in a parenthesis like this.where it could have been

(4 - 9/2)² = (5 - 9/2)²

so , i just wanted to easy you.

 

[Kimbo]

whoa...your all like..robots or calculators..
simply amazing..yet..i dont understand it..

 

[Daelin]

well,dont be so sure.

the thing you are calling modulo is what i call absolute value,anyway...
I dont have any of these. i just put '{' and '[' characters to make the expression more understandable.

I know you don't have it in your demonstration, and that's the whole problem. Because when you want to... blah, I hate math in english because I don't know the terms. Well, when you have

√a = √b

and you want to rise the equality at power 2, you do not get

a=b

but you get

|a|=|b|

.

Why? (x+y)² is always positive. So √(x+y)² is also positive. We can't have √ from something negative (for even grade).

Example: x=-3 an y=1.
√(x+y)² = √(-3+1)² = √(-2)² = √4 = 2
So, we could've simply taken √(x+y)²=|-3+1|=|-2|=2.

That's why absolute value is required, and that's why how I wrote the equality is correct, and how you wrote it isn't!

~Daelin

 

[Raiju]

Let me guess your math's grade, 11? :?

 

[Daelin]

Math's grade? You mean, my anual mark at math? Nah, I've got 8 at math. We are doing much more complicated things at school. Right now, studying complex numbers, we already got to their trigonometric form and now are doing all sort of equations (pretty simple I might add).

As for algebra, we are studying functions. Finished seeing what injective, surjective and bijective functions are and how to find the inversal of a bijective function. Sorry if the words do not match in english, I tried to "translate" them the best way I could.

That's all about my math!

~Daelin

 

[olofmoleman]

I will prove to you that 4 = 5

What a usefull way to fill time...

 

[Xeridanus]

4 - 9/2 = 5 - 9/2

this line should be

± (4 - 9/2) = ± (5 - 9/2)

because when you take the square root of something you have two possible answers a positivee one and a negative one. you then have four possible solutiions and not all of them have to be right.

you then get:

-4 + 4.5 = 5 - 4.5 which is true or
4 - 4.5 = -5 + 4.5 which is also true.

but the other two combinations are wrong.

 

[Daminon]

Math's grade? You mean, my anual mark at math? Nah, I've got 8 at math. We are doing much more complicated things at school. Right now, studying complex numbers, we already got to their trigonometric form and now are doing all sort of equations (pretty simple I might add).

~Daelin

:shock: Ehm how much math do you actually study in Romanina? What comes in high school and collage?

I can compare to high school in Sweden where people goes for three years, starts at 16. There are five grades of math:
A - Repeat of prevous math and start with real equation solving. Some 2:nd grade equations but not complete ones. Also making function graphs.
B - More advanced equations and complete 2:nd grade equations.
C - Geometric series. Logaritms. But most of all deriavtes (correct english?).
D - Trigonometri and integrals.
E - Complex number and more advanced integrals. Polar graphs.

And all these courses are not standard. Only a few programs at high shool goes further than C.
How does it look in Romania? Have you learned parametic graphs?

 

[Nantuko_Husk]

I knew this had a problem , just i wanted someone to find it.
I am have been preety sure most people would have got confused in the square difference

where 4² - 2 * 4 * (9/2) + (9/2)² is [4 - (9/2)]²

but it is simple

(a+b)² = a² + b² + 2ab

so ( 4 - 9/2 )² according to the above formula is

4² + (9/2)² + 2 * 4 + 9/2

arent those same. some just didnt want to understand it and kept saying that i was wrong there,

------

@daelin

hahaaaha omg at alebra we have just finished those injective , syrjective and bijective stuff.


now we are studying limits.

I have 9 at maths. XD

but the class i am is called 'scientific profilization' and we do mostly maths , chemistry and physics.

omg i had today exams at physics,waves,it was not too hard though...but i wrote fine;

 

[Daelin]

We don't have your education system.
Grades 1-4: Primary School
Grades 5-8: Gymnasium
Grades 9-12: Highschool

You start at the age of 7 so I should be in 9th grade, but I started school at 6 so I am in 10th grade. So, let's see:

In 9th grade we learnt trigonometry, functions (revision grade 1 and learnt grade 2), mathematical induction, vectors, progressions, and some other stuff I can't remember.

Grade 10 we made by now functions (injective, surjective, bijective), logarithms, radicals (n grade, since grade 2 is square root and we made it in 7th grade), and I dunno what's going to come. I saw some specific functions (logarithimical and other stuff) plus we will make probabilities.

As for geometry part, we started learning complex numbers, and we will begin with analitical geometry as well in the second semester. There are probably other stuff but I didn't look in the book to see. I don't care. Math is one of the subjects at which I suck.

Derivates, limits and stuff like that... I think that's 11th grade math. Yeah, 11th grade will surely suck.

Oh, and Nantuko, you're older than me. I wouldn't be surprised if you started learning limits.

~Daelin

 

[Raiju]

you didnt get the question Daelin, we too have this same system, sole exception for they are called "serials" not "grades"

the 8 grade in romania must give really hard things, i'm in 8 grade too but i studied this year only functions, trigonometrical resolves and some really bad graphic interpretations that i forgot. i hate math, i almost lose this year because of math

i was actuallying asking you whats your, note, i mean, when the end of the year comes you receive a paper with your school prowess from 1 to 10. then i joked you took 11 got it?

 

[Xeridanus]

I knew this had a problem , just i wanted someone to find it.
I am have been preety sure most people would have got confused in the square difference

where 4² - 2 * 4 * (9/2) + (9/2)² is [4 - (9/2)]²

but it is simple

(a+b)² = a² + b² + 2ab

so ( 4 - 9/2 )² according to the above formula is

4² + (9/2)² + 2 * 4 + 9/2

arent those same. some just didnt want to understand it and kept saying that i was wrong there,

Yes that is almost right... Its's probably just a typo but I'll change it anyway.

4² + (9/2)² - 2 * 4 * 9/2

 

[Nantuko_Husk]

Yeah! I meant the 'note' raiju said like degrees,thats the nine I have. but i have done til now 11 years of school , so grade 11? anyway.

 

[Raiju]

finally someone understands me, cookies n' tequila for nantuko!

 

[Jacek]

We don't have your education system.
Grades 1-4: Primary School
Grades 5-8: Gymnasium
Grades 9-12: Highschool

You start at the age of 7 so I should be in 9th grade, but I started school at 6 so I am in 10th grade. So, let's see:

In 9th grade we learnt trigonometry, functions (revision grade 1 and learnt grade 2), mathematical induction, vectors, progressions, and some other stuff I can't remember.

Grade 10 we made by now functions (injective, surjective, bijective), logarithms, radicals (n grade, since grade 2 is square root and we made it in 7th grade), and I dunno what's going to come. I saw some specific functions (logarithimical and other stuff) plus we will make probabilities.

As for geometry part, we started learning complex numbers, and we will begin with analitical geometry as well in the second semester. There are probably other stuff but I didn't look in the book to see. I don't care. Math is one of the subjects at which I suck.

Derivates, limits and stuff like that... I think that's 11th grade math. Yeah, 11th grade will surely suck.

Oh, and Nantuko, you're older than me. I wouldn't be surprised if you started learning limits.

~Daelin

crap... I want to learn that too ;] I am moving to Romania w00000t

I am in kinda like 9th grade (from 6 years old) and we are learning angles in polygons (calculating), algebraic expressions... we should have in last month of school trygonometric functions (Sin and Cos)...

 

[Daminon]

I want to learn the formula for solving 3rd grade equations. I have found three but no one worked.

 

[Pepper]

ooh...im grade 10 and i don't get most of what you say. here, hs ends at grade 11.

 

[Xeridanus]

Where exactly is there?