Does need help with math

How to choose the sign of the radical in the denominator of the formula for the distance from a point to a line.

What are the coordinates of the midpoint of ab? ,1/2) /2,-1) ,-3/2) /2,-2)

What is the range of the function? f(x)=-2|x+1|? a. all real numbers. b. all real numbers less than or equal to 0. c. all real numbers less than or equal to 1. d. all real numbers greater than or equal to 1