原式=-1+6+9-8-5=5+6+9-8-5=11+9-8-5=20-8-5=12-5=7
原式=(-1/3--2/3)+(1/4-3/4)+1/2=-1+1/2+1/2=-1+1=0
第三个无能为力了
-7+6+9-8-5
=(-7+6)+(9-8)-5
=-1+1-5
=-5
-1/3+1/2+1/4-2/3-3/4
= (-1/3-2/3)+1/2+(1/4-3/4)
=-1+1/2-1/2
=-1
123.75-1又3/4-29又2/5-3又3/5+112又1/3
=123.75-1.75-(29又2/5+3又3/5)+112又1/3
=122-33+112又1/3
=89+112又1/3
=201又1/3
-7+6+9-8-5=-1+1-5=-5
-1/3+1/2+1/4-2/3-3/4=-1-1/2+1/2=-1
123.75-1又3/4-29又2/5-3又3/5+112又1/3=122-23+122又1/3=201又1/3
123•75-1又