(1/2+1/4+1/6+1/8)+(1/3+1/6+1/9+1/12)-(1/4+1/8+1/12+1/16)
=1/2(1+1/2+1/3+1/4)+1/3(1+1/2+1/3+1/4)-1/4(1+1/2+1/3+1/4)
=(1+1/2+1/3+1/4)(1/2+1/3-1/4)
=25/12×7/12
=175/144
这是我在静心思考后得出的结论,
如果不能请追问,我会尽全力帮您解决的~
如果您有所不满愿意,请谅解~其它两道可以吗……1.1×(4+21/97)+40.9÷(5+2/19)-4.09×9/97=4.4+1.1×21/97+40.9×19/97-4.09×9/97=4.4+1/97(1.1×21+19×40.9－4.09×9)=4.4+1/97[1.1×21+4.09×(190-9)]=4.4+1/97(1.1×21+4.09×181)=4.4+7.87=12.27 39×148/149+148×86/149+48×74/149=(78+172+48)×74/149=298×74/149=148