1949×(1/51-1/2000)+51×(1/1949-1/2000)-2000×(1/1949+1/51)+3
=1949/51-1949/2000+51/1949-51/2000-2000/1949-2000/51+3
=(1949-2000)/51-(1949+51)/2000+(51-2000)/1949+3
=-1-1-1+3
=0
1.先去括号,用乘法分配在计算
=1949×1/51-2000×1/51-1949×1/2000-51×1/2000+51×1/1949-2000×1/1949+3
=-1-1-1+3=0
把括号拆了,再重新排列~
1949×(1/51-1/2000)+51×(1/1949-1/2000)-2000×(1/1949+1/51)+3
=1949/51-1949/2000+51/1949-51/2000-2000/1949-2000/51+3
=(1949-2000)/51-(1949+51)/2000+(51-2000)/1949+3
=-1-1-1+3
=0