Is there a simplified equation for doing something like this:
$(1x) + (2x) + (3x) + (4x) + (5x)$
but the number it goes to (the example goes to 5 ) can be variable?
Is there a simplified equation for doing something like this:
$(1x) + (2x) + (3x) + (4x) + (5x)$
but the number it goes to (the example goes to 5 ) can be variable?
Yes, it's $\sum_{k=1}^n kx = x\sum_{k=1}^n k = {nx(n+1)\over 2}.$