# serina's questions at Yahoo! Answers regarding sigma notation

Staff member

#### MarkFL

Staff member
Hello serina,

1.) I would begin by observing the series can be written as:

$$\displaystyle S=4(-6)^0+4(-6)^1+4(-6)^2+\cdots$$

and so we have:

$$\displaystyle S=4\sum_{k=0}^{\infty}(-6)^k$$

2.) I would begin by observing the series can be written as:

$$\displaystyle S=9^3+10^3+11^3+12^3+\cdots+n^3$$

and so we have:

$$\displaystyle S=\sum_{k=9}^n k^3$$

To serina and any other guests viewing this topic, I invite and encourage you to post other pre-calculus problems here in our Pre-Calculus forum.

Best Regards,

Mark.