Correct-Incorrect Equation

let a=b

a^2=ab

a^2-b^2=ab-b^2

(a+b)(a-b)=b(a-b)

a+b=b

2b=b

2=1

This series of equations is given to prove that 2=1.Although this may appear correct there is a fallacy in this.At step 5 both sides have been divided by a-b.But a=b.So a-b=o.An d, no number can be divided by 0.

Note by Vishal S
3 years, 4 months ago

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i found a solution when we compare 1=2 with a=b => a is not equal to b thats it any doubts reply me ill say

- 3 years, 4 months ago

I had given the solution that it is incorrect.Then how can you give a solution for a incorrect question

- 3 years, 4 months ago

that's what iam saying a is not = b you considered a wrong equation in the beggening

- 3 years, 4 months ago

How can you tell that $$a \neq b$$.I had provided the word let a=b.If a=b in the above series of equation, we get 1=2

- 3 years, 4 months ago

We had that too in a quiz after we discussed trigonometric ratios :D The questions was "Prove that 2=1" I kept going to 1=0 until we were given a hint - difference of two squares :D

- 3 years, 4 months ago