I(r,Y)+ Ye(^-r) -r

(12 points) An economist claims that he has found evidence to support the assumption that investment expenditure increases with Y. More specifically, I relies on both r and Y, and: I( r, Y ) = Year-r. 1) (6 points) Derive the government-purchase multiplier under this new assumption. (Recall that in the Keynesian cross model, r is fixed at r, but Y is endogenous.) 2) (6 points) Derive the taxation multiplier under this new assumption