The number N of aids cases diagnosed to date (in thousands) is approximated by the equation
N = -0.37x^2 + 59.5x + 247.26, where x is the number of years since 1990. Assuming that this equation remains valid through the year 2011, determine when the number of diagnosed cases of aids was or will be 1.2 million.
I understand that in the question, N = 1.2 million. I then used the quadratic formula to find x. However, when I replaced N with 1.2, I got the wrong year and thus the wrong answer. What should N be to get the right answer?