Hi!

I was reading this page on this site: . At the bottom, there is a proof for the distributivity of multiplication over addition for natural numbers. However, I think there is a step that seems suspect, that is:

x*(y+z) + x = (x*y + x*z) + x

That step looks like it uses the very thing which is being proven here. Is it so, or am I overlooking something rather trivial?

Currently, I'm a third-year student of theoretical physics in university, so I think I should know enough to understand this.

JJe
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