Applications of quadratic equations: Maxima and minima
Between 1989 and 1997 the percentage of households with incomes of $100,000 or more (in 1997 dollars) is modeled by f(x) = .071x2 - .426x + 8.05, where x = 0 represents the year 1989. (Source; American Demographics, January 1999). Based on this model when did the percent of people in this income level reach its minimum? You do not have to graph the function.