336除以(19乘3加27)怎样简便运算
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1/2X3X4X5+1/3X4X5X6+1/4X5X6X7.1/97X98X99X100=?=1/3[1/2*3*4-1/3*4*5]+1/3[1/3*4*5-1/4*5*6]+1/3[1/4*5*6
45乘3除以5加7减10(8乘9)=45×3÷5+7-10×(8×9)=27+7-720=34-720=-686
裂两项相消法:完全是凑出简单的几项和差的形式进行化简:步骤一:待定系数法-----设An=1/[n(n-1)(n-2)];(n>=3,n∈N*);令An=A/(n-2)+B/(n-1)+C/n;通分后
原式=(1/2)×(1-1/3)+(1/2)×(1/3-1/5)+(1/2)×(1/5-1/7)+……+(1/2)×(1/2005-1/2007)=(1/2)×(1-1/3+1/3-1/5+1/5-1
10/3*3/7+20/3*3/7=(10/3+20/3)*3/7=30/3*3/7=30/719/5*1/9+1/5/9=19/5/9+1/5/9=(19/5+1/5)/9=20/5/9=4/9
原式通项可以写成1/(n*(n+1)*(n+2))n=1,2,...,2000原式n从1到2000上述各项的和.而1/(n*(n+1)*(n+2))=(1/n)+(1/(n+1))-(2/(n+2))
5.38×4.9+6.6×5.38-5.38÷2/3=5.38×4.9+6.6×5.38-5.38×1.5=5.38×(4.9+6.6-1.5)=5.38×10=53.8
4.5625
5.6除以0.75加4/3乘0.4=5.6÷4分之3+3分之4*0.4=5.6*3分之4+3分之4*0.4=(5.6+0.4)*3分之4=6*3分之4=8
x/15×25+140=3x5x/3+140=3x式子两边同时乘以3,得5x+420=9x4x=420x=105
1/[n*(n+1)*(n+2)]=[1/n-1/(n+1)]/(n+2)=[1/n-1/(n+2)]/2-[1/(n+1)-1/(n+2)]=[1/n-2/(n+1)+1/(n+2)]/21/(1*
答案是9再问:过程再答:1×3×24+2×6×48+3×9×72=9×(1×2×4+2×4×8+3×6×12)再答:约分即可再答:分子每一个都是分母相应项的9倍再问:.....再问:要过程。再答:1×
4936*(0.75*42.7-0.573*25+57.3)/3=4936*(0.75*42.7-25*0.573+100*0.573)/3=4936*[0.75*42.7+(100-25)*0.57
1/4*2003+2005*25+2004*1/4=1/4*(2003+2005+2004)=1/4*6012=15033375÷27x12=125x12=125x4x3=15006.6+0.6x20
直接计算最简便1204乘(38加405除以27)=1204*(38+15)=1204*53
5.23÷4/3+5.25x0.25=(5.25-0.02)x3/4+5.25x1/4=5.25x3/4+5.25x1/4-0.02x3/4=5.25(3/4+1/4)-0.015=5.235满意请点
19乘12除以57乘375除以3=228÷57×(375÷3)=4×125=500
1×2+3-4+5÷6÷7=1?