Question

टू प्लस टू इज इक्वल टू फाइव

Answer 1

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2 + 2 = 4.It is a universal truth , but a few people had proved that 2 + 2 = 5, there is a mistake in that solution.Let's figure out that mistake.
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We know that,

 2 + 2 = 4   

By adding and subtracting 9/2 in RHS.

 2 + 2 = 4 - 9/2  +  9/2 

Now by squaring ( 4 - 9/2 ) and rooting it.

2 + 2 = √( 4 - 9/2)^2  + 9/2  ( Mistake that will be explained further )

2 + 2 = √( 16 + 81/4 - 36 )     +  9/2 

2 + 2 = √ ( - 20 + 81/4 )   +  9/2

2 + 2 = √( 25 - 45 + 81/4 )   + 9/2

2 + 2 = √ [ 5^2 + ( 9/2 ) ^2 - 2 * 5 * 9/2 ]   + 9/2

2 + 2 = √ ( 5 - 9/2 ) ^2    + 9/2

2 + 2 = 5 - 9/2 + 9/2

2 + 2 = 5 .

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Now go on mistake ,

We often think that squaring a number and then rooting it always give the same number, but it is not truth.There we did  √(4 - 9 /2)^2 .Here 4 - 9/2 = - 0.5 that is a negative number,so we can't do this.

Ex:  After squaring -1 and then rooting it give two values that is +1 and -1.

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