2²-2³-······2¹⁰S=2³+······+2¹⁰ ①2S=2⁴+······+2¹¹ ②②-①得S=2¹¹-2³所以:2²-2³-······2¹⁰=2²-(2¹¹-2³)=2²+ 2³-2¹¹=4+8-2¹¹=12-2¹¹