Question

初一数学 化简

[x-x/(x+1)]*[(x+1)/(x^2+3x+2)]÷[(x^2-2x)/(x^2-4)]
一楼的纯粹是瞎扯

Answer 1

1、2(2a2＋9b)＋3(－5a2－4b) 2、a＋(5a－3b)－(a－2b)
3、3n－[5n＋(3n－1)] 4、a－(5a－3b)＋(2b－a)
1、(3a2 ＋7bc－4b2)－(5a2－3bc－2b2)＋abc，其中a＝5，b＝1/3，c＝3
2、(5a2－3b2)＋[(a2＋b2)－(5a2＋3b2)]，其中a＝－1，b＝1
1、2(2a2＋9b)＋3(－5a2－4b)
=(8a+18b)+(-30a-12b)=8a-30a+18b-12b=-22a+6b

2、a＋(5a－3b)－(a－2b)
=a+5a-a+(-3b+2b)=5a-b

3、3n－[5n＋(3n－1)]
=3n-(5n+3n-1)=3n-(8n-1)=3n-8n+1=-5n+1

4、a－(5a－3b)＋(2b－a)
=a-5a+3b+2b-a=(a-5a-a)+(3b+2b)=5b-5a

1、(3a2 ＋7bc－4b2)－(5a2－3bc－2b2)＋abc，其中a＝5，b＝1/3，c＝3
解：原式=(6a+7bc-8b)-(10a-3bc-4b)+abc
=6a+7bc-8b-10a+3bc+4b+abc
=(6a-10a)+(7bc+3bc)+(-8b+4b)+3abc
=-4a+10bc-4b+3abc
将a＝5，b＝1/3，c＝3代入得

Answer 2

[x-x/(x+1)]*[(x+1)/(x^2+3x+2)]÷[(x^2-2x)/(x^2-4)]
=x²/(x+1)×(x+1)/(x+1)(x+2)×(x²-4)/(x²-2x²)
=x²/(x+1)×(x+1)/(x+1)(x+2)×(x-2)(x+2)/x(x-2)
=x/(x+1)

Answer 3

x/(x+1)

详解：（x^2）/(x+1)/(x+2)*(x+2)/x=x/(x+1)

Answer 4

x'2/x+1