Maths is wrong ?

[lamchopz]

Again the 1=0 proofs I saw a cool Calculus one a while back, lemme see if I can remember it

1²=1
2²=2+2=4
3²=3+3+3=9
x²=x+x+x...[x times]

d (x²) = 2x
dx

d (x+x+x...[x times]) = 1+1+1... [x times] = x.
dx

2x = x, defined at the least for all nonnegative integers x. Where's the error? (I actually don't know concretely myself)

Forgive me if I'm wrong. But isn't differentiation only valid when the function is continuous?

f(x) = x² above is clearly discrete.