这个数列怎么求和?当n=1,m=0.1当n=2,m=0.1*2+(1-0.1)*0.1*1当n=3,m=0.1*3+(1-0.1)*0.1*2+(1-0.1)^2*0.1*1…………当n=n时候,m=n*0.1+(n-1)*0.1*(1-0.1)+.+1*0.1*(1-0.1)^(n-1)求怎么求和
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![这个数列怎么求和?当n=1,m=0.1当n=2,m=0.1*2+(1-0.1)*0.1*1当n=3,m=0.1*3+(1-0.1)*0.1*2+(1-0.1)^2*0.1*1…………当n=n时候,m=n*0.1+(n-1)*0.1*(1-0.1)+.+1*0.1*(1-0.1)^(n-1)求怎么求和](/uploads/image/z/8512254-54-4.jpg?t=%E8%BF%99%E4%B8%AA%E6%95%B0%E5%88%97%E6%80%8E%E4%B9%88%E6%B1%82%E5%92%8C%3F%E5%BD%93n%3D1%2Cm%3D0.1%E5%BD%93n%3D2%2Cm%3D0.1%2A2%2B%EF%BC%881-0.1%EF%BC%89%2A0.1%2A1%E5%BD%93n%3D3%2Cm%3D0.1%2A3%2B%281-0.1%29%2A0.1%2A2%2B%281-0.1%29%5E2%2A0.1%2A1%E2%80%A6%E2%80%A6%E2%80%A6%E2%80%A6%E5%BD%93n%3Dn%E6%97%B6%E5%80%99%2Cm%3Dn%2A0.1%2B%28n-1%29%2A0.1%2A%281-0.1%29%2B.%2B1%2A0.1%2A%281-0.1%29%5E%28n-1%29%E6%B1%82%E6%80%8E%E4%B9%88%E6%B1%82%E5%92%8C)
这个数列怎么求和?当n=1,m=0.1当n=2,m=0.1*2+(1-0.1)*0.1*1当n=3,m=0.1*3+(1-0.1)*0.1*2+(1-0.1)^2*0.1*1…………当n=n时候,m=n*0.1+(n-1)*0.1*(1-0.1)+.+1*0.1*(1-0.1)^(n-1)求怎么求和
这个数列怎么求和?
当n=1,m=0.1
当n=2,m=0.1*2+(1-0.1)*0.1*1
当n=3,m=0.1*3+(1-0.1)*0.1*2+(1-0.1)^2*0.1*1
…………
当n=n时候,m=n*0.1+(n-1)*0.1*(1-0.1)+.+1*0.1*(1-0.1)^(n-1)
求怎么求和
这个数列怎么求和?当n=1,m=0.1当n=2,m=0.1*2+(1-0.1)*0.1*1当n=3,m=0.1*3+(1-0.1)*0.1*2+(1-0.1)^2*0.1*1…………当n=n时候,m=n*0.1+(n-1)*0.1*(1-0.1)+.+1*0.1*(1-0.1)^(n-1)求怎么求和
我县确定一下
m=n*0.1+(n-1)*0.1*(1-0.1)+(n-2)*0.1*(1-0.1)^2+.+1*0.1*(1-0.1)^(n-1)这样是吗?
0.9m= n*0.1*(1-0.1)+(n-1)*0.1*(1-0.1)^2+……+2*0.1*(1-0.1)^(n-1)+1*0.1*(1-0.1)^n
上下相减,m-0.9m=n*0.1-0.1*(0.9+0.9^2+……+0.9^(n-1))-1*0.1*(1-0.1)^n
=n*0.1-0.1*(0.9+0.9^2+……+0.9^(n-1)+0.9^n
=0.1n-0.1*(0.9*(1-0.9^n)/(1-0.9)) (等比数列求和这个会吧)
=0.1n-0.9(1-0.9^n)
m=n-9(1-0.9^n)