What is the purpose of this task?

Question

Programming

Calculating the sum/product of N elements of an infinite number series?
And the formula is also indicated, I don’t understand.
y \u003d (-3) 6 (-9) 12 (-15)
This formula is also available.
Give at least some example, I myself want to decide.

Answer 1

In short:
There are numbers: -3, 6, -9, 12, -15, 18, -21, 24, ... and so on ad infinitum
, the task is that you need to calculate the sum / product of N elements of such a sequence.
For example, let's find the sum of 3 elements: [ -3 + 6 - 9 = -6 ], the answer is -6 .
It all depends on N and where we start counting from.

Answer 2

As far as I understand, this is a given series, and from it you can derive a formula for a series.
In general, you described very poorly what you need.
what I see here is: y = E(i=1, i->inf) (((-1)^N) * N * 3)

Answer 3

Apparently, a series is given (in this case: -3, 6, -9, 12, -15, ...), and some N. We need to find the sum and product of the first N elements.
In this case, with N=4, the sum will be -3+6-9+12=6, and the product will be 1944.
With N=5, the sum will be -9, and the product will be -29160.