英语数学综合题1.The fraction 2/(x^2-3x+2)can be written as an infin

来源：学生作业帮编辑：拍题作业网作业帮分类：综合作业时间：2024/04/28 14:21:19

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.
如果能随便解决问题 15分就是你的啦

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

(sat数学)for a certain fraction,if 2 is added 英语的2道题目~1._____(see) from the sky,people look as small as an what is the biggest number that can be written w In the fraction x/y,where x and y are positive integers,what 英语翻译Modern x-ray techniques only use of fraction of the x-ra 再问一道数学综合题.已知.f(x)=x^3-3ax(1).求f(x)的单调区间（2）.a=1,求证：4x+y+m=0不可英语二补充二、Reading（3道小题,Advertisement can be thought of “as the we use "X" as the ---for an unknown quantity. if one light-year≈95000000000000km,it can be written as km i 一道看不懂的英文题1.If 2x < 100 and x is an integer,how many of the 2 GMAT数学if 10^50-74 is written as an integein base10 notation. 一道化简题（吧）For what integer b can the expression x^2+bx+7 be fa