What is ∑[100 (-4) n-1] equal to?

4 is on top

n=1 on bottom

4

∑ [100 (-4) n-1]

n=1

Once again, since this is summation notation:

Start at the number on the bottom. Plug in that number to the equation on the right, plug in the next number into the equation on the right, and so on, until you get to the number on top. Plug in that final number, and after you get the solution, add all the solutions you have all together.

One thing though: the bottom number cannot be bigger than the number on top.

n=1; 100 x (-4) x (1) - 1 = - 401

n=2; 100 x (-4) x (2) - 1 = - 801

n=3; 100 x (-4) x (3) - 1 = - 12001

n=4; 100 x (-4) x (4) - 1 = - 16001

-401-801-12001-16001 = - 29204