英语数学综合题1.The fraction 2/(x^2-3x+2)can be written as an infinite series.Find the sum of the first four terms of the series espansion for x=-1 and x=-2.2.Many different seven digit integers can be formed by permuting the digits 1-7;like 1
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英语数学综合题1.The fraction 2/(x^2-3x+2)can be written as an infinite series.Find the sum of the first four terms of the series espansion for x=-1 and x=-2.2.Many different seven digit integers can be formed by permuting the digits 1-7;like 1
英语数学综合题
1.The fraction 2/(x^2-3x+2)can be written as an infinite series.Find the sum of the first four terms of the series espansion for x=-1 and x=-2.
2.Many different seven digit integers can be formed by permuting the digits 1-7;like 1234567 and 7653412.What is the sum of all seven digit numbers.
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英语数学综合题1.The fraction 2/(x^2-3x+2)can be written as an infinite series.Find the sum of the first four terms of the series espansion for x=-1 and x=-2.2.Many different seven digit integers can be formed by permuting the digits 1-7;like 1
1.
2/(x^2-3x+2)=2/(1-x)-1/(1-x/2)
=2(1+x+x^2+x^3+x^4+...)-(1+x/2+x^2/4+x^3/8+x^4/16+...)
=1+3x/2+7x^2/4+15x^3/8+31x^4/16+...
当x=-1,-2是,用展开式的前四项求和：
S(-1)=1-3/2+7/4-15/8=-5/8
S(-2)=1-3+7-15=-10
2.
所有这样的7位数之和为：
6!*(1+10+10^2+10^3+10^4+10^5+10^6)*(1+2+3+4+5+6+7）
=720*28*1111111
=22399997760
1. 分式2/(x²-3x+2)可以展为无穷级数。求当x=-1 和 x=-2时的前4项之和。
2. 许多不同的7位整数可排为1-7; 如1234567和7653412。所有这些7位整数的和为多少？
1。分数2 /（χ^ 2 - 3x+2）可以写成无穷级数。找到了前4个为X系列espansi之和x=- 1和x =- 2。 （增根问题）
2。许多不同的7位数字的整数，可形成排样的数字1-7;如1234567和7653412. 所有7位数字的总和为：7*（1+2+3+4+5+6+7）=196