Question

1. What is the sum of the series? 2. What is the sum of the series?

Answer 1

Answer:

1).90

2).-10

Step-by-step explanation:

1).

(3(1)^2)+(3(2)^2)+(3(3)^2)+(3(4)^2)

  3      +     12    +    27    +    48

=90

2). (-5(3)+20)+(-5(4)+20)+(-5(5)+20)+(-5(6)+20)

     (-15+20)  +  (-20+20)  + (-25+20)  +  (-30+20)

           5       +       0         +       -5       +      -10

=-10

Answer 2

So for finite series like these, you just plug in each number for k that it tells you. The first says the sum of 3k^2 from k=1 to k=4. Just plug integer k between 1 and 4 into the equation and add them together:

3(1^2)+3(2^2)+3(3^2)+3(4^2)=90

Same for the next one, except this is for all values of k between 3 and 6:
(-5(3)+20)+(-5(4)+20)+(-5(5)+20)+(-5(6)+20)=-10