A line passes through (2, -1) with slope 3. What is the equation of the line in point-slope form?
A. y - 1 = 3(x + 2)

B. 3(y + 2) = x - 1

C. y - 2 = ( 1/3 x + 1)

D y + 1 = 3(x - 2)

The average number of vehicles waiting in line to enter a parking lot can be modeled by the function f left parenthesis x right x squared over 2 left parenthesis 1 minus x right parenthesis endfraction , where x is a number between 0 and 1 known as the traffic intensity. find the rate of change of the number of vehicles waiting with respect to the traffic intensity for the intensities (a) xequals0.3 and (b) xequals0.6.