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need help bad very confused

Select the sum of the series: Σ^5∨k-1^k^2
 
a. 55
b. 56
c. 200
d. 225

3 Answers by Expert Tutors

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Steve S. | Tutoring in Precalculus, Trig, and Differential CalculusTutoring in Precalculus, Trig, and Diffe...
5.0 5.0 (3 lesson ratings) (3)
0
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.
Michael F. | Mathematics TutorMathematics Tutor
4.7 4.7 (6 lesson ratings) (6)
0
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.
Parviz F. | Mathematics professor at Community CollegesMathematics professor at Community Colle...
4.8 4.8 (4 lesson ratings) (4)
-1
Problem is not clear. You need to write it properly.