Find {{CMD_20}}five{{CMD_21}} examples where this ``trick'' works, and {{CMD_22}}five{{CMD_23}} examples where it doesn't work. {{CMD_24}} Start with limits of fractions that you know how to compute. Then take the derivative of the numerator and the denominator, and see if the new limit equals the old limit or not. {{CMD_25}} {{CMD_26}} {{CMD_27}} {{CMD_28}}