8、不对,改正:
原式=(3.25+5又3/4)+[(-2又3/5)+(-8.4)]
=9+(-11)
=-2
第9题对了,第10题第二步不对,改正:
原式=[28+(-18)]+[6+(-16)]
=10-10
=0
第11题又错啦,改正:
原式[(-3又3/4)+(-1.25)]+(1.125+4又7/8+2又1/7)
=(-5)+8又1/7
=3又1/7
12、原式=(3.64+0.06)+(1.78+1/10)+[(-33/100)+(-5.25)+(-0.2)]
=3.7+1.98+(-5.78)
=-0.1
8.8.4那少了一个负号,结果没错
10.6-16=-10,结果是0
11.第二行抄掉-3又3/4,结果3又1/7
12.1.78+3.64+0.1-0.33+0.06-5.25-0.2
=1.78+3.64+0.06+0.1-0.33-5.25-0.2
=5.58-5.78=-0.2
12.原式=1.78+3.64+0.1-0.33-10.06-5.25-0.2=-10.52