1/2+1/6+1/12+1/20+1/30+1/42= 2+4+6+...+2010= (5/9-5/6+1/4)÷(-1/36)= (-19 18/19)*38= 都用简便计算
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![1/2+1/6+1/12+1/20+1/30+1/42= 2+4+6+...+2010= (5/9-5/6+1/4)÷(-1/36)= (-19 18/19)*38= 都用简便计算](/uploads/image/z/106810-34-0.jpg?t=1%2F2%2B1%2F6%2B1%2F12%2B1%2F20%2B1%2F30%2B1%2F42%3D+2%2B4%2B6%2B...%2B2010%3D+%285%2F9-5%2F6%2B1%2F4%29%C3%B7%28-1%2F36%29%3D+%28-19+18%2F19%29%2A38%3D+%E9%83%BD%E7%94%A8%E7%AE%80%E4%BE%BF%E8%AE%A1%E7%AE%97)
1/2+1/6+1/12+1/20+1/30+1/42= 2+4+6+...+2010= (5/9-5/6+1/4)÷(-1/36)= (-19 18/19)*38= 都用简便计算
1/2+1/6+1/12+1/20+1/30+1/42= 2+4+6+...+2010= (5/9-5/6+1/4)÷(-1/36)= (-19 18/19)*38= 都用简便计算
1/2+1/6+1/12+1/20+1/30+1/42= 2+4+6+...+2010= (5/9-5/6+1/4)÷(-1/36)= (-19 18/19)*38= 都用简便计算
1/2+1/6+1/12+1/20+1/30+1/42=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=1-1/7=6/7
2+4+6+...+2010=2*(1+2+3+...+1005)=2*1005*1006/2=1011030
(5/9-5/6+1/4)÷(-1/36)= -36*(5/9-5/6+1/4)= -20+30-9=1
抱歉最后一个你题目少写了运算符号了吧,
1/2+1/6+1/12+1/20+1/30+1/42=1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=6/7
2+4+6+...+2010=2*{[(1+1005)*1005]/2}=1005*1006=(1000+5)*1006=1006000+5030=1011030
(5/9-5/6+1/4)÷(-1/36)=(5/9-5/6+1/...
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1/2+1/6+1/12+1/20+1/30+1/42=1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=6/7
2+4+6+...+2010=2*{[(1+1005)*1005]/2}=1005*1006=(1000+5)*1006=1006000+5030=1011030
(5/9-5/6+1/4)÷(-1/36)=(5/9-5/6+1/4)*(-36)=-(20-30+9)=1
(-19 18/19)*38=-(19*38+18/19*38)=-(19²*2+18*2)=-[(20-1)²*2+36]
=-[(400-40+1)*2+36]=-(361*2+36)=-(722+36)=-758
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