Great Summation!

Algebra Level 1

Evaluate :

∑ n = 1 31 3 ( − 1 ) n − 1 \large \color{#20A900} { \displaystyle \sum_{n=1}^{31} 3(-1)^{n-1} }


The answer is 3.

Anish Harsha by Anish Harsha , 20, India

This section requires Javascript.
You are seeing this because something didn't load right. We suggest you, (a) try refreshing the page, (b) enabling javascript if it is disabled on your browser and, finally, (c) loading the non-javascript version of this page . We're sorry about the hassle.

1 solution

Akshat Sharda
Oct 30, 2015

∑ n = 1 31 3 ( − 1 ) n − 1 = 3 ∑ n = 1 31 ( − 1 ) n − 1 = 3 ⋅ [ 16 ( 1 ) + 15 ( − 1 ) ] = 3 \displaystyle \sum^{31}_{n=1} 3(-1)^{n-1}=3 \displaystyle \sum^{31}_{n=1} (-1)^{n-1}=3\cdot [16(1)+15(-1)]=\boxed{3}

4 Helpful 0 Interesting 0 Brilliant 0 Confused

How 3 ⋅ [ 16 ( 1 ) + 15 ( − 1 ) ] 3\cdot [16(1)+15(-1)] ?

Munem Shahriar - 3 years, 8 months ago

0 pending reports

×

Problem Loading...

Note Loading...

Set Loading...