Write the sum using summation notation.
-$$0 + 2 + 6 + 12 + 20$$
A) $\sum _ { i = 1 } ^ { 5 } ( 2 i - 2 )$

B) $\sum_{i=1}^{5}\left(i^{2}+i\right)$

C) $\sum _ { i = 1 } ^ { 5 } \left( i ^ { 2 } + i - 2 \right)$

D) $\sum _ { i = 1 } ^ { 5 } \left( i ^ { 2 } - i \right)$

Question

Write the sum using summation notation.
-$$0 + 2 + 6 + 12 + 20$$
A) $\sum _ { i = 1 } ^ { 5 } ( 2 i - 2 )$

B) $\sum_{i=1}^{5}\left(i^{2}+i\right)$

C) $\sum _ { i = 1 } ^ { 5 } \left( i ^ { 2 } + i - 2 \right)$

D) $\sum _ { i = 1 } ^ { 5 } \left( i ^ { 2 } - i \right)$

Quizplus · Accepted Answer

The given sequence can be written as:
$$0 + 2 + 6 + 12 + 20 = 2\cdot 0 + 2 \cdot 1 + 2 \cdot 3 + 2 \cdot 6 + 2 \cdot 10$$
So the sum can be expressed as:
$$\sum_{i=1}^{5} (2i^2-2i)=\sum_{i=1}^{5} (i^2-i)$$
This matches with the option D.

Write the Sum Using Summation Notation 0+2+6+12+200 + 2 + 6 + 12 + 200+2+6+12+20

Write the Sum Using Summation Notation $0 + 2 + 6 + 12 + 20$