Can someone explain to me the basics of ∑ and how it is used in binomial expansion. I will reward best answer, thanks.
∑ simply means "add them up"
usually there are indicators as to which ones you add up, which are placed at the bottom and top of the summation sign.
Consider the set of numbers A = (1, 3, 5, 8, 9)
There are 5 of them. Now let us consider
5
∑ A = 1 + 3 + 5 + 8 + 9 sometimes written at ∑A
1
when all are to be added. We CAN get "tricky"
3
∑A = 3 + 5 which means add up the second and third elements of the set
2
Or even trickier:
∑2A = 2x1 + 2x3 +2x5 +2x 8 +2x9 or multiply each element by 2 before adding
(note, I left the subscripts off the above--which I shall continue to do.
or howse about dis:
∑A^2 = 1^2 + 3^2 + 5^2 + 8^2 + 9^2 = 1 + 9 + 25 + 64 + 81
Pretty straight forward, really. I recomember how it gave me problems at
first until I sat down and ground it out.
Sometimes, you get a double summation. Hence, consider:
1 5
2 0
3 4
2 3
∑ ∑ (1 + 2 + 3) + (5 + 0 + 4)
1 1
∑ 6 + 9 = 15
always,
tony
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Verified answer
∑ simply means "add them up"
usually there are indicators as to which ones you add up, which are placed at the bottom and top of the summation sign.
Consider the set of numbers A = (1, 3, 5, 8, 9)
There are 5 of them. Now let us consider
5
∑ A = 1 + 3 + 5 + 8 + 9 sometimes written at ∑A
1
when all are to be added. We CAN get "tricky"
3
∑A = 3 + 5 which means add up the second and third elements of the set
2
Or even trickier:
∑2A = 2x1 + 2x3 +2x5 +2x 8 +2x9 or multiply each element by 2 before adding
(note, I left the subscripts off the above--which I shall continue to do.
or howse about dis:
∑A^2 = 1^2 + 3^2 + 5^2 + 8^2 + 9^2 = 1 + 9 + 25 + 64 + 81
Pretty straight forward, really. I recomember how it gave me problems at
first until I sat down and ground it out.
Sometimes, you get a double summation. Hence, consider:
1 5
2 0
3 4
2 3
∑ ∑ (1 + 2 + 3) + (5 + 0 + 4)
1 1
2
∑ 6 + 9 = 15
1
always,
tony