数学题“1/4+1/28+1/70+1/130”怎样计算?
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数学题“1/4+1/28+1/70+1/130”怎样计算?数学题“1/4+1/28+1/70+1/130”怎样计算?数学题“1/4+1/28+1/70+1/130”怎样计算?原式=1/(1*4)+1/
数学题“1/4+1/28+1/70+1/130”怎样计算?
数学题“1/4+1/28+1/70+1/130”怎样计算?
数学题“1/4+1/28+1/70+1/130”怎样计算?
原式=1/(1*4)+1/(4*7)+1/(7*10)+1/(10*13)
=(1/3)*(1-1/4)+(1/3)*(1/4-1/7)+(1/3)*(1/7-1/10)+(1/3)*(1/10-1/13)
=(1/3)*(1-1/4+1/4-1/7+1/7-1/10+1/10-1/13)
=(1/3)*(1-1/13)
=4/13.
原式=1/3*（1-1/4+1/4-1/7+1/7-1/10+1/10-1/13）
=1/3*12/13
=4/13
原式=1/3*[(1-1/4)+(1/4-1/7)+(1/7-1/10)+(1/10-1/13)]=1/3*(1-1/13)=4/13
原式=1/3*（1-1/4+1/4-1/7+1/7-1/10+1/10-1/13）
=1/3*(1-1/13)
=1/3*12/13
=4/13