2.4乘以8.6加7.5乘以8.6加0.86
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![2.4乘以8.6加7.5乘以8.6加0.86](/uploads/image/f/130850-26-0.jpg?t=2.4%E4%B9%98%E4%BB%A58.6%E5%8A%A07.5%E4%B9%98%E4%BB%A58.6%E5%8A%A00.86)
先通分,分母为15.15分之一乘以括号8加6加10,等于一又十五分之九
1÷(5*6*7)+1÷(6*7*8)+1÷(7*8*9)=1/7*(1/30+1/48+1/72)=1/7*49/720=7/720
10除以8加3.96乘以12.5%加2.04乘以16分之2=10/8+3.96*12.5%+2.04*2/16=1/8*(10+3.96+2.04)=16/8=26000减105乘以36=6000-1
2000*1999-1999*1998+1998*1997-1997*1996=1999*(2000-1998)+1997*(1998-1996)=1999*2+1997*2=2000*4-2-6=7
100乘以(-2)乘以(-8)乘以0.01=(100×0.01)×(2×8)=1×16=16
(1+2*3+4)*5+(6*7+8)*9=505
每一项都是n*(n+1)*1/(n+2),可以化成(n-1)+2/(n+2)所以原式=(0+1+2+3+...+47)+2(1/3+1/4+1/5+...+1/50)前面一个括号用等差数列求和公式就行
7.2乘以0.2加2.4乘以1.4=2.4×0.6+2.4×1.4=2.4×(0.6+1.4)=2.4×2=4.8
750.75乘以55加7.5乘以4.5=0.75×55+0.75×45=0.75×(55+45)=0.75×100=75
7.5×23+31×2.5=2.5×69+31×2.5=2.5×(69+31)=2.5×100=250
625乘以625乘以625乘以8乘以8乘以8乘以8乘以2乘以2乘以2乘以2乘以2=(625*8)(625*8)(625*8)*8*2*2*2*2*2=5000*5000*5000*8*2*2*2*2*
32.2*0.4+178*0.04=32.2*0.4+17.8*0.4=0.4*(32.2+17.8)=0.4*50=204.83*7.5+75*0.51=7.5*(4.83+5.1)=7.5*9.9
2009加2009乘以2008乘以0.25加2008乘以2009乘以0.75减8乘以2009乘以0.125乘以2008=2009+2009×2008×(0.25+0.75-8×0.125)=2009+
320×(-0.25)-147×(-0.125)+253×1/8+72×(-1/4)=-80+18.375+31.625-8=-38
0.15×0.8×12.5+8×3×0.125=1.5×8×0.125+8×3×0.125=(8×0.125)×(1.5+3)=4.5
111111*999999+999999*555555=999999*(111111+555555)=999999*666666=(1000000-1)*666666=666666000000-666
再答:OK,发过去了再答:采纳吧
2乘以3分之一加3乘以4分之一加4乘以5分之一……加7乘以8分之一=6-(1/3+1/4+1/5+1/6+1/7+1/8)=6-1又61/280=4又219/280再问:有没有更简便的啊???拜托了。