Saturday

March 28, 2015

March 28, 2015

Posted by **Laura** on Saturday, June 16, 2007 at 8:17am.

If you mean the sum of the first 20 terms, beginning with k=1, of

ak = 3k - 5,

that would be -20 x 5 = -100

PLUS the sum of the first 20 terms of

ak = 3k

The latter is 3 times the sum of

1+2+3+...20 ,

or 3*(20)(21)/2= 630

So the answer is 630 - 100 = 530

**Answer this Question**

**Related Questions**

Precalculus - Find the sum of the first 50 terms of the sequence 2,4,6,8...

arithmetic - 1. The first and last term of an A.P are, a and l respectively, ...

arithmetic - 1. The first and last term of an A.P are, a and l respectively, ...

Further mathematics - An exponential sequence (GP)of positive terms and a linear...

math - Hi. I'm having trouble with the summation of n from i=2 of ((2^n-i)(2^n...

Algebra - Express the sum below using summation notation. Use 1 as the lower ...

Calculus - The problem I have is a summation from 1 to infinity for (-1)^n/n. I ...

Algebra - I have a few problems I need some help with. The first is Evaluate ...

Geometric - 1) The sum of last three terms of GP having n terms is 1024 time the...

calc help - consider the function f(x)= x^2/4 -6 Rn is the Riemann sum where the...