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Potironette · 08:52 PM

So..infinity is a number? What does "closed form" mean?

For math homework, there's a problem that says to find the ratio, fifth term, and the nth term of a sequence: 5, 5^c+1, 5^2c+1, 5^3c+1, ...

I got that a₅ = 5^4c+1 and that a_n = 5^(n-1)c+1.
But what is the ratio? Is it just 5 or is it 5^(n-1)c+1 or something else?

Also, how does S_n = (1/2)(n(2a +(n-1)d)) = n((a₁+a₂)/2) ?
(That is, how does (1/2)(n(2a +(n-1)d)) turn into n((a₁+a₂)/2) ?)
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How does it work that the magnetic field lines points north inside a magnet? What really is a magnetic field? If I remember right it's something about where the north point of the compass would point but..that means if a compass were somehow stuck inside a magnet it would point north. What's actually going on..?

Potironette petite fantaisiste			#321
	So..infinity is a number? What does "closed form" mean? For math homework, there's a problem that says to find the ratio, fifth term, and the nth term of a sequence: 5, 5^c+1, 5^2c+1, 5^3c+1, ... I got that a₅ = 5^4c+1 and that a_n = 5^(n-1)c+1. But what is the ratio? Is it just 5 or is it 5^(n-1)c+1 or something else? Also, how does S_n = (1/2)(n(2a +(n-1)d)) = n((a₁+a₂)/2) ? (That is, how does (1/2)(n(2a +(n-1)d)) turn into n((a₁+a₂)/2) ?) --------------------------------------------- How does it work that the magnetic field lines points north inside a magnet? What really is a magnetic field? If I remember right it's something about where the north point of the compass would point but..that means if a compass were somehow stuck inside a magnet it would point north. What's actually going on..? Last edited by Potironette; 04-24-2017 at 08:52 PM.
		Posted 04-24-2017, 06:40 PM