发布网友 发布时间:2024-10-21 15:02
共1个回答
热心网友 时间:2024-11-01 02:23
应该是1/(X+2)+1/x=32/x(x+2) 等式两边乘以x(x+2)
x+(x+2)=32
2x+2=32
2x=30
x=15
1/x+2+1/x=32/x^2+2x
(x+x+2)/x(x+2)=32/x(x+2)
2x+2=32
2x=30
x=15
(X +2)((32/X) +1)-50=0
(X-8)的平方=0
解得X=8
令2^(1/2)x=a
则2^x=a^2
a^2+a-42=0
(a+7)(a-6)=0
因为2^(1/2)x 〉0
所以a+7=0不成立
a=6
2^(1/2)x=6
(1/2)x=log(2)6
x=2log(2)6=log(2)36
这里用到一个公式
1/[x(x+1)]=1/x-1/(x+1)
同理,
1/[(x+1)(x+2)]=1/(x+1)-1/(x+2)
1/[(x+2)(x+3)]=1/(x+2)-1/(x+3)
∴1/[(x+1)(x+2)]+1/[(x+2)(x+3)]+...+1/[(x+2007)(x+2008)]
=[1/(x+1)-1/(x+2)]+[1/(x+2)-1/(x+3)]+...+[1/(x+2007)-1/(x+2008)]
=1/(x+1)-1/(x+2)+1/(x+2)-1/(x+3)+...+1/(x+2007)-1/(x+2008)
=1/(x+1)-1/(x+2008)
=2007/[(x+1)(x+2008)]
∴2007/[(x+1)(x+2008)]=2007/(3x+6024)
(x+1)(x+2008)=3x+6024
x+1=3
x=2
望采纳,谢谢O(∩_∩)O
x=0
1+1/2+1/3>13/12
x=1
1/2+1/3+1/4<13/12
所以x=1
1/(x+2)+4x/(x平方-4)=1+2/(x-2)
4x/(x平方-4)=1+2/(x-2) -1/(x+2)=1+[2(x+2)-x-2]/(x²-4)=1+(x+2)/(x²-4)
4x/(x²-4)-(x+2)/(x²-4)=1
(4x-x-2)/(x²-4)=1
3x-2=x²-4
x²-3x-2=0
x=(3±√17)/2
1/(x+2) + 1/x = 32/(x²+2x)
(2x+2)/(x²+2x) = 32/(x²+2x)
2x+2 = 32
2x = 30
x = 15
解:两边同乘以x(x+2)得:
2(x+2)+x(x+2)=x²
2x+4+x²+2x=x²
2x+2x=-4
4x=-4
x=-1
检验:x=-1是方程的解
x+2=y ①
30/x-30/y=1/2 ②
由①式得:y=x+2
把y=x+2带入②式得:
30/x-30/(x+2)=1/2
化简得:x²+2x-120=0
(x+1)²=121
x+1=±11
x₁=10或x₂=-12