Refer to the graph below. 13) Find the y-intercept/s. 14) Find the x-intercept/s. 15) List the interval/s of which the function is increasing. 16) List the interval/s of which the function is decreasing. 17) Find the maximum. 18) Find the minimum. 19) List the values of x at which the maximum occurs. 20) List the value/s of x at which the minimum occurs.