2=1?

infinity-infinity is undefined

Speaking of food. I'm having cottage pie for lunch!

x-y=0 as x=y.

You can't divide by zero

(x + y)(x - y) = y(x - y)

Dividing out the common term, (x - y) results in

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^^ In this part. Lordy, lordy me

Didi

Its already been solved. Dividing by (x-y) is fine. You need to look through the solution again

Regardless of if it's been solved, you can't divide by (x - y) if x=y. That's how you break maths

Whats going on here???? Nando your forumla is being questioned again.....do I have to take back my apology?

I did not invent the formula! I just copied. Its supposed to be incorrect.

Both Didi Hamann and I have the same hypothesis. He is saying if you divide by (x-y), when we already know x=y, then its an illegal step. As x-y equals 0 and you cannot divide anything by 0.

And I'm saying pretty much the same thing

You're right - you've divided by 0 as x = y for all x and y. You broke maths

Actually you're more incorrect for trying to treat x and y as separate entities when you've told us they're the same.