For the quadratic function f(x)= -x + 8x. answer parts (a) through (c). (a) Graph the quadratic function by determining whether its graph opens up or down and by finding its vertex, axis of symmetry, y-intercept, and x-intercepts, if any. Does the graph off open up or down? O down O up What are the coordinates of the vertex? The vertex of the parabola is (Type an ordered pair. Use integers or fractions for any numbers in the expression.) What is the equation of the axis of symmetry? The axis of symmetry is (Type an equation.) What is/are the x-intercept(s)? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. The x-intercept(s) is/are (Type an integer or a decimal. Use a comma to separate answers as needed.) OB. There are no x-intercepts. What is the y-intercept? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. The y-intercept is (Type an integer or a decimal.) OB. There is no y-intercept. Use the graphing tool to graph the function. Click to enlarge graph (b) Determine the domain and the range of the function. The domain offis (Type your answer in interval notation.) The range of fis (Type your answer in interval notation.) (c) Determine where the function is increasing and where it is decreasing. The function is increasing on the interval TRAFA in intamaalntation + 2