The relationship between the graph and its coefficients

The example describe the relationship between the graph of a quadratic function and its coefficient. You need to answer the following questions. Question A: if the graph is open upward, then
the coefficient of the x square term of a quadratic function should be positive ot negative? Question B: How to determine the sign of the x term of the quadratic function?
Question C: How to determine the sign of the constant term of a quadratic function? Question D: How to determine whether b^{2} - 4ac > 0? Question E: How to determines whether the a + b + c > 0?
Question E: How to determine whether a - b + c > 0?