A negative minus a negative equals

What is the standard form of -5x^2+2x^4-11+x^3+3x

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%

2pointswhich of the following appear in the diagram below? check all that apply. d a. zcdeов. сеo c. aéo d. zdce