要写出过程:(1)(-25)-(-18)-(+5)-(+12)(2)(-3/5)+(4/5)-1/5-3/2+7/4第二条错了。是(2)-3/5+4/5-1/5-3/2+7/4

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要写出过程:(1)(-25)-(-18)-(+5)-(+12)(2)(-3/5)+(4/5)-1/5-3/2+7/4第二条错了。是(2)-3/5+4/5-1/5-3/2+7/4

要写出过程:(1)(-25)-(-18)-(+5)-(+12)(2)(-3/5)+(4/5)-1/5-3/2+7/4第二条错了。是(2)-3/5+4/5-1/5-3/2+7/4
要写出过程:(1)(-25)-(-18)-(+5)-(+12)(2)(-3/5)+(4/5)-1/5-3/2+7/4
第二条错了。是(2)-3/5+4/5-1/5-3/2+7/4

要写出过程:(1)(-25)-(-18)-(+5)-(+12)(2)(-3/5)+(4/5)-1/5-3/2+7/4第二条错了。是(2)-3/5+4/5-1/5-3/2+7/4
分析,根据规律,负负得正,负正得负,正负得负
1,
(-25)-(-18)-(+5)-(+12)
=-25+18-5-12
=-7-17
=-24
2,
-3/5+4/5-1/5-3/2+7/4
=1/5-1/5-3/2+7/4
=7/4-3/2
=(7-6)/4
=1/4

:(1)(-25)-(-18)-(+5)-(+12)= - 25+18-5-12= -24(2)-3/5+4/5-1/5-3/2+7/4=(-3/5+4/5-1/5)-2/3+7/4=0-2/3+7/4=13/21