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need help bad very confused

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3 Answers

I think Michael’s guess is correct.

I’d write it this way: sum[k=1,5][k^2].
(See page 3 of http://www.purplemath.com/modules/mathtext.htm)

Let’s see if we can solve this without using a formula.

S = sum[k=1,5][k^2] = 1^2 + 2^2 + 3^2 + 4^2 + 5^2.
S = (1 + 4) + (9 + 16) + 25
S = 5 + (25 + 25)
S = 5 + 50
S = 55.
Wild guess Σk=1k=5  k2, the sum of the squares of the first five natural numbers.
=(5)(5+1)(2×5+1)⁄6=55
The general formula is Σk=1k=n k2=(n)(n+1)(2n+1)/6

Comments

Students should learn how to write problems properly. The way they write causes more confusion.

Comment

Problem is not clear. You need to write it properly.