Question

Use sigma notation to represent the sum of the first seven terms of the following sequence: 4, 10, 16, ...

Ο Σ -4+6n
Ο Σ 4 + 6n
Ο Σ 2+6n
Ο Σ -2+ 6n

Answer 1

∑-2 + 6n

Explanation:

4, 10, 16, ......

7 terms

nth term is a + (n - 1)*d

= 4 + (n -1 )*6

= 4 + 6n - 6

= -2 + 6n

so sigma notation would be

∑-2 + 6n

u can also check terms

n = 1 -> -2 + 6 = 4

n = 2 -> -2 + 6*2 = 10

n = 3 -> -2 + 6*3 = 16

Answer 2

`\sum_(n = 0)^(6) 4 + 6n \\ n = 0 \rightarrow4\\ n = 1 \rightarrow10 \\ n = 2 \rightarrow16 \\ n = 3 \rightarrow22 \\ n = 4 \rightarrow28 \\ n = 5 \rightarrow34 \\ n = 6 \rightarrow40`