One of the oldest math trick

[Faraz.Ahmed]

Just for a change I am posting this math trick. This is just based on simple elementary algebra. Basically this starts with the equation x = x and after applying simple algebraic formula, drive the result x = 2x. Any idea how it is possible?

x = x

x = x

- Subtract x from both sides.

x - x = x - x

- Take x common from left hand side of equation

x ( x - x ) = x - x

- Apply ( a - b ) = ( a - b ) ( a + b ) on right hand side of equation.

x ( x - x ) = ( x - x ) ( x + x)

- Divide both side by ( x - x )

x = ( x + x )

x = 2x

- How?

 

[Bunna]

x-x = 0

you are not allowed to divide any numerator by zero. Anything divide by zero==> infinity

 

[Ali raza babar]

apply a sq - b sq when a and b have different values not like x sq - x sq

 

[Faraz.Ahmed]

x-x = 0

you are not allowed to divide any numerator by zero. Anything divide by zero==> infinity

You are right.
strictly speaking, divide by zero is undefined (not infinity)

 

[Ali-NZ]

WTF.............. I only know........... x-x means female & x-y means male :lol:

 

[Bunna]

You are right.
strictly speaking, divide by zero is undefined (not infinity)

strictly?? really? may be I am not good in math. But check it, 0/0 is undefined. 1/0=>infinit. 1/infinity=0.

, but

is undefined, as is

. Check it.

 

[younis123]

Theformula is (a[SUP]2[/SUP]-b[SUP]2[/SUP]) and not (a[SUP]2[/SUP]-a[SUP]2[/SUP]). You can not apply the formula for same entity as it

equals to zero.

 

[Faraz.Ahmed]

strictly?? really? may be I am not good in math. But check it, 0/0 is undefined. 1/0=>infinit. 1/infinity=0.

, but

is undefined, as is

. Check it. I got 98/100 in Intermediate Part 2.

Wow. did u top the board?

 

[laalaobulbul]

Yes you are right

x-x = 0

you are not allowed to divide any numerator by zero. Anything divide by zero==> infinity

 

[Bunna]

Wow. did u top the board?

No, there are many people who worked hard, i am just a small potato chips.

 

[mohammadi]

Theformula is (a[SUP]2[/SUP]-b[SUP]2[/SUP]) and not (a[SUP]2[/SUP]-a[SUP]2[/SUP]). You can not apply the formula for same entity as it

equals to zero.

yes you are very right , you really cant apply the formula

 

[Faraz.Ahmed]

Theformula is (a[SUP]2[/SUP]-b[SUP]2[/SUP]) and not (a[SUP]2[/SUP]-a[SUP]2[/SUP]). You can not apply the formula for same entity as it

equals to zero.

The problem is not the formula. you can have (a[SUP]2[/SUP]-a[SUP]2[/SUP])

x ( x - x ) = ( x - x ) ( x + x) ---> is valid equation.

the problem is next step. you cannot divide by zero.

 

[mohammadi]

The problem is not the formula. you can have (a[SUP]2[/SUP]-a[SUP]2[/SUP])

x ( x - x ) = ( x - x ) ( x + x) ---> is valid equation.

the problem is next step. you cannot divide by zero.

i never read this formula throughout my studies. can someone explain how come (a[SUP]2[/SUP]-b[SUP]2[/SUP]) and (a[SUP]2[/SUP]-a[SUP]2[/SUP]) can both give the same ans. ?

 

[younis123]

The problem is not the formula. you can have (a[SUP]2[/SUP]-a[SUP]2[/SUP])

x ( x - x ) = ( x - x ) ( x + x) ---> is valid equation.

the problem is next step. you cannot divide by zero.

Brother,you can’t have (a[SUP]2[/SUP]-a[SUP]2[/SUP]), why?

Youget (a[SUP]2[/SUP]-b[SUP]2[/SUP]) when you multiply (a+b) (a-b) = a[SUP]2[/SUP]-ab+ab+b[SUP]2[/SUP](ab-ab=0) so are left with (a[SUP]2[/SUP]-b[SUP]2[/SUP]).

Applythe same logic on other side i.e (a[SUP]2[/SUP]-a[SUP]2[/SUP]) = (a+a)(a-a) = a[SUP]2[/SUP]-a[SUP]2[/SUP]+a[SUP]2[/SUP]-a[SUP]2[/SUP]
Netresult here is “Zero”.

Conclusion: We can’t have (a[SUP]2[/SUP]-a[SUP]2[/SUP]).

 

[Irfan Chohan]

Both logics are valid.

(a[SUP]2[/SUP]-b[SUP]2[/SUP]) is not same as (a[SUP]2[/SUP]-a[SUP]2[/SUP]). Also (a[SUP]2[/SUP]-a[SUP]2[/SUP]) is not valid bcoz the sum in the parenthesis is Zero.

Anything divided by Zero is infinity.

 

[jaanmark]

Nature has answer that do not waste the time get up and make wazu and do two rakat nafal thanks

 

[Sadia Hashmi]

there is also a solution here