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1、有理数重点题解一计算:1. (-0.6)+0.08+(-3.4)+0.92+1.98 2. (-3)+4+18.3+(-2)+1 =0.08+0.92+1.98-0.6-3.4 =4-2+1-3+18.3 =3.98-4 =2-2+18.3 =-0.2 =18.33.(-3)+(-4)+6+(-3) 4.| -|+(-)+|-|+| =-3-4-3+6 =-+ =-10+6 =0+1 =-4+(-) =1 =-4+ =-3二 计算：1 %（-0.3）%(-11)%(-1) 2. (-3)%(-246) %(-)% = - % =-%246% =-1% =-1%246% =-15 = -63.
2、(-0.125) %8 - (-0.2) %(-0.5) 4. (-1)- (-4)% =-0.125%8-0.2%0.5 =-1-(-)% =-1-0.1 = -1 -(-2)=-1.1 =-1+2 = 15. 39%(-12) 6. 15%(-+) - 24%(-) = (40-)%(-12) =15%(-)+15%- 24%-24%(-) = 40%(-12)- %(-12) =-9+5 10 + =-480+ =-14+11 =-479 = -3+ = -27. 120%(3-5- 7) 另解:120% (3-5- 7) =120%(-) =120%3-5- (8-) =120%-12
3、0%-120% =120%(3-5-8)+120%-120%+120% =456-700-965 =120%(-10)+96-100+4 =- 1200 =-12008. (-12.5)(-2)(-8) (+) 9. 3%(3-7)% = -12.5%8% =%( -) =-100 =%-% =3-7 =-4三.已知a=5,b=-3,求|a+2|+|-a|-|+b|的值.解: |a+2|+|-a|-|+b|=|5+2|+|-5|-|+(-3)|=7+5-3=9四.已知|2x-1|+|y-1|=0,求代数式3xy的值解：|2x-1|0 ,|y-2|0 且|2x-1|+|y-1|=0|2x-1|=0，且|y-2|=0由|2x-1|=0得，x= 由 |y-2|=0得，y=23x2y=3×()2×2=有理数的分类: 有理数 欢迎访问 3 / 3文档可自由编辑打印