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1.计算: (1)(-25)+(-7); (2)(-13)+5; (3)(-23)+0; (4) 45+(-45),= -32,= -8,= -23,= 0,2.计算(表示出应用法则的过程): (1)(-3.5)+(4.1); (3)( )+( ); (2)( ) +( ); (4)( )+( );,解: (1)(-3.5)+(4.1)=+(4.1-3.5)=0.6 (2)( )+( )= -( + )= (3)( ) +( )= -( )= (4)( )+( )= -( )=,3.计算:,(1)10+(-4);,(2)(+9)+7;,(3)(-15)+(-32);,(4)(-9)+0;,(5)100+(-100);,(6)(-0.5)+4.4;,(7)(-1.5)+(1.25);,(8),= 10-4 = 6,= 9+7 = 16,= -(15+32)= -47,= -9,= 100-100 = 0,= 4.4-0.5 = 3.9,= -(1.5-1.25)= -0.25,