Question

Which of the following is equivalent to the sum of negative 3n minus 4 for n equals 4 to 8 ?

Answer 1

These are the choices:
–110

–88

88

110

Answer 2

And this is the problem: \[\sum_{n=4}^{8} -3n -4\]

Answer 3

\[\sum_{n=4}^{8}-3n-4=\sum_{n=4}^{8}-3n-\sum_{n=4}^{8}4\]

Answer 4

So how do I proceed from here? And thank you by the way.

Answer 5

\[=-3\sum_{n=4}^{8}n-\sum_{n=4}^{8}4\]

Answer 6

so what do I do now?

Answer 7

substitute

Answer 8

oh and the result is -110

Answer 9

(-3*4-4)+(-3*5-4)+(-3*6-4)+(-3*7-4)+(-3*8-4)=-110
I've done the substitution for you also