$1=2$

Algebra Level 2

$a=b$

$a^2=ab$

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

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

$a+b=b$

$2a=a$

$2=1$

What's wrong with this proof?

You've divided by 0 The a's and b's have been added up incorrectly Nothing's wrong, the proof is correct and

1=2

a≠b

The factorisation is incorrect

2 solutions

Kay Xspre
Mar 28, 2016

Division by $a-b$ is the division by zero, which is strictly not allowed as it is undefined

. .
Apr 19, 2021

By the first row, $a = b$ means that $a - b = 0$ .

Then, look at the fourth row.

He or she divided the number by zero whether $a$ or $b$ is zero or not.

If you divide a number in a complex number by zero, you'll know it.

It is UNDEFINED!!!!!!