Math ? *i think it's b but i just want to make sure*

what is the unit vector of: v: < -6, -8> ?

a. < ⅗, ⅘ >
b. < -⅗, -⅘ >
c. < ⅘, ⅗ >
d. < -⅘, -⅗ >

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%

Ineed someone to me answer my question i have to have this done and knocked out

Rewrite the following quadratic functions in intercept or factored form. show your work. f(x) = 3x^2 - 12