Question

What is the sum of the sereis. I dont know what to do??

Answer 1

Given:

`\sum ^(24)_(c\mathop=1)(155-3c)`

Let's evaluate the expression.

Apply the formula for summation of a conatant:

`\sum ^n_(k=1)c=cn`

Split the summation into smaller summations using summation rules:

`\sum ^(24)_(c=1)155-3\sum ^(24)_(c=1)c`

Apply the formula:

Solving further:

`(155\ast24)-(-3\cdot(24(24+1))/(2))`
`\begin{gathered} (3720)+(-3\cdot(24(25))/(2)) \\ \\ (3720)+(-3\cdot(600)/(2)) \\ \\ (3720)+(-3\cdot300) \\ \\ 3720+(-900) \\ \\ 3720-900=2820 \end{gathered}`

ANSWER:

2820