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You are not logged in. #1 20131217 07:45:09
building an equationHi, #2 20131217 07:52:39
Re: building an equationSo, you want the sum 1+2+3+...+(n1)+n? The limit operator is just an excuse for doing something you know you can't. “It's the subject that nobody knows anything about that we can all talk about!” ― Richard Feynman “Taking a new step, uttering a new word, is what people fear most.” ― Fyodor Dostoyevsky, Crime and Punishment #3 20131217 08:37:14
Re: building an equationhi Mitchell The diagram below shows where it comes from. If you stack up n then n1, then n2 ....... 3, 2, 1 squares it makes a sort of right angled triangle. Then make the same again but turn this stack upsidedown and slot it into the triangle to make a rectangle. The rectangle is 'n' high and n+1 wide so its area is n(n+1). But we've made twice the sum you want, so divide by 2. That's it. Bob Last edited by bob bundy (20131217 08:39:16) You cannot teach a man anything; you can only help him find it within himself..........Galileo Galilei 