Question

The number of new accounts opened at a credit union in the years 2001 to 2006 can be approximated by the model N(t)= -80.6t^2+2100t+12000, where 11 <= t <= 16, with t = 11 corresponding to 2001. Using this model and your graphing calculator, determine the year in which the number of new accounts opened was maximum

Answer 1

the max is on the axis of symmetry of the parabola

t = -b / 2a = -2100 / (2 * -80.6)