Please help, I’m just trying to pass the class lol

Which value is not a solution of 8x^3 – 1 = 0

The first-serve percentage of a tennis player in a match is normally distributed with a standard deviation of 4.3%. if a sample of 15 random matches of the player is taken, the mean first-serve percentage is found to be 26.4%. what is the margin of error of the sample mean? a. 0.086% b. 0.533% c. 1.11% d. 2.22%

If f(x) = x+8 and g(x) = 4x- 3, find (f+g)(x)