问几道有理数计算题,①(-5)+(-3)-(-2)+(+7)-(-9)②-1/3-1/2+1/4-1/6

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问几道有理数计算题,①(-5)+(-3)-(-2)+(+7)-(-9)②-1/3-1/2+1/4-1/6
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问几道有理数计算题,①(-5)+(-3)-(-2)+(+7)-(-9)②-1/3-1/2+1/4-1/6
问几道有理数计算题,
①(-5)+(-3)-(-2)+(+7)-(-9)
②-1/3-1/2+1/4-1/6

问几道有理数计算题,①(-5)+(-3)-(-2)+(+7)-(-9)②-1/3-1/2+1/4-1/6
①(-5)+(-3)-(-2)+(+7)-(-9)
=-5-3+2+7+9
=10
这一条只要记住括号前面是+号的,把括号去掉就不用变号;括号前面是减号的,去括号就要变号(加号变减号,减号就变加号)
②-1/3-1/2+1/4-1/6
=-4/12-6/12+3/12-2/12
=(-4-6+3-2)/12
=-9/12
=-3/4
这一条简单,把分母都变成一样的就形了,不过要记住,分母成以多少,分子也要同时成以多少!

①=-5-3+2+7+9=10
②=-4/12-6/12+3/12-2/12=-9/12=-3/4