(a) Construct a time series plot. D' What type of pattern exists? The time series plot exhibits a downward linear trend. The time series plot exhibits an upward curvilinear trend. The time series plot exhibits a downward curvilinear trend. The time series plot exhibits an upward linear trend. (b) Using Minitab or Excel, develop a quadratic trend equation that can be used to forecast users (in millions). (Round your numerical values to one decimal place.) Tt=