Use summation formulas to rewrite the expression without the summation notation . sum i=1 ^ n 2i^ 3 -3i n^ 4

Factor out 1/n⁴, and distribute the sum over each term:

Recall the following formulas:

So we have

check above link.

graphically?   well, you graph them both, the solutions is where they both intersect each other, since there are two solutions, meaning they will meet twice, or namely the linear will run into the quadratic curve twice, and where they meet, those x,y coordinates are the solutions to the system.