4
二次方是^2,三次方是^3,依此类推“^”按住SHIFT再按"6"键,但必须是英语输入法原式=(1/7xy)^2*14(xy)^2*(1/4x)^5=((1/7xy)*14xy)^2*(1/4x)^5=4*(1/4*4)^5=1/(2^19)