1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10=?

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1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10=?
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1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10=?
1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10=?

1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10=?
1/2×2+1/4×3+1/6×4+1/8×5+…1/18×10
= 1/(2*1)*2+1/(2*2)*3+1/(2*3)*4+……1/(2*9)*10
= 1/2(1/1*2+1/2*3+1/3*4+……+1/9*10)
= 1/2(1/1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10)
= 1/2(1/1-1/10)
= 9/20

懒得人`````没什么好答的

9
∑(n+1)/2n
n=1

原式
=1/2[1/(1*2)+1/(2*3)+1/(3*4)+1/(4*5)......1/(9*10)]
=1/2[1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5......-1/9+1/9-1/10]
=(1/2)*(9/10)
=9/20

1、2、2、4、3、6、4、( )、( 1+2+3/6+1/4= 巧算：(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)(1+1/2+1/3+1/4+1/5)*(1/2+1/3+1/4+1/5+1/6)-(1+1/2+1/3+1/4+1/5+1/6)*(1/2+1/3+1/4+1/5)===== 简算：1/1*2+1/2*3+1/3*4+1/4*5+1/5*6 1/2-（3/4-3/8）,1/2+1/4-1/6 ,2/3+（1/2+1/4）,1/2-（3/4-3/8）,1/2+1/4-1/6 ,2/3+（1/2+1/4）, 1/2-（3/4-3/8）, 1/2+1/4-1/6 , 2/3+（1/2+1/4）,1/2-（3/4-3/8）, 1/2+1/4-1/6 , 2/3+（1/2+1/4）, 1/2-（3/4-3/8）,1/2+1/4-1/6 ,2/3+（1/2+1/4）,1/2-（3/4-3/8）,1/2+1/4-1/6 ,2/3+（1/2+1/4）, 简算：24×(1/2+1/3-1/4-1/6) （1/2+1/3+1/4+1/6）*24 1+1+1+1+1+1+1+1+1+2+5+4+8+3+6+2+1+4等于多少? （1- 1/100)(1- 1/99) .....(1- 1/4)(1- 1/3)(1- 1/2) (-1 1/2)*(-1 1/3)*......(-1 1/6)*(-1 1/7) [2^4+1/4)(4^4+1/4)(6^4+1/4)(8^4+1/4)(10^4+1/4)】/[1^4+1/4)(3^4+1/4)(5^4+1/4)(7^4+1/4)(9^4+1/4)] (-2/3)+(-1/6)+1/4-1/2 习题2.8 -2/3+(-1/6)-(-1/4)-1/2 -1/2+（-1/6）-（-1/4）-2/3 1/1*3+1/2*4+1/3*5+1/4*6+.+1/100*102=? 1+1+1+1+11+-1-1-1-1-2-3-4-5-6等于 1-1/2+1/3-1/4+1/5-1/6+1/7.-1/50=?