Question

What’s is the sum of the series?

Answer 1

44

Explanation:

`\sum\limits_(k=1)^4(2k^2-4)\to a_k=2k^2-4\\\\for\ k=1:\\\\a_1=2(1)^2-4=2(1)-4=2-4=-2\\\\for\ k=2:\\\\a_2=2(2)^2-4=2(4)-4=8-4=4\\\\for\ k=3:\\\\a_3=2(3)^2-4=2(9)-4=18-4=14\\\\for\ k=4:\\\\a_4=2(4)^2-4=2(16)-4=32-4=28\\\\\sum\limits_(k=1)^4(2k^2-4)=-2+4+14+28=44`