已知22*4=1
已知2/2*4=1/2-1/4,2/4*6=1/4-1/6求1/2*4+1/4*6+......+1/48*50小学数学题
1/2*4+1/4*6+......+1/48*50=1/2(1/2-1/4+1/4-1/6+.... 1/48-1/50)=(1/2)*(1/2-1/50)=6/25.
因为:2/2×4=1/2-1/4; 2/4×6=1/4-1/6; …… 2/48×50=1/48-1/50 所以:1/2×4+1/4×6+……+1/48×50 =2×(1/2×4+1/4×6+……+1/48×50)÷2 =(2/2×4+2/4×6+……+2/48×50)÷2 =(1/2-1/4+1/4-1/6+……+1/48-1/50)÷2 =(1/2-1/50)÷2 =(24/50)÷2 =12/50=6/25
1/2*4+1/4*6+......+1/48*50 =1/2-1/4+1/4-1/6+1/6......-1/48+ 1/48-1/50=1/2-1/50=12/25
答:题目最后“+1”不妥,应为: 求 1/(2*4)+1/(4*6)+...+1/[2n(2n+2)]。 则 1/(2*4)+1/(4*6)+...+1/[2n(2...详情>>
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