Home > Student activities > National Maths Day > National Maths Day 2014 > ‘Proof’ that 2 = 1
‘Proof’ that 2 = 1
let a = b, then a2 = ab
a2 - b2 = ab-b2
(a-b)(a+b) = b(a-b)
a+b = b, substituting gives b+b = b
2b = b therefore 2 = 1
Where is the error made?
let a = b
then a2 = ab
a+b = b
substituting b+b = b
2b = b
2 = 1
You need to be aware that a – b = 0. This false proof relies on dividing both sides of an equation by zero which should not be done.
Yes
