5. What is the Standard deviation for the following set
of data?
6,4,9, 5, 5, 4,5

The answer is 5.4 because you'll add them up and divide by 7

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.

there are infinitely many solutions.