A parabola has a vertex at (0,0). The equation for the directrix of the parabola is x = –4. In which direction does the parabola open? up down right left.

Monitors manufactured by tsi electronics have life spans that have a normal distribution with a standard deviation of 1800 hours and a mean life span of 20,000 hours. if a monitor is selected at random, find the probability that the life span of the monitor will be more than 17,659 hours. round your answer to four decimal places.

What is the equation of a line that passes through points (0, 4) and (-4,-8)?

You eat $0.85 for every cup of hot chocolate you sell. how many cups do you need to sell to earn $55.25