中科新闻网商场垃圾桶 捡丝袜:初二数学题!高手来!在线=哦!
来源：百度文库 编辑：中科新闻网 时间：2024/04/29 15:06:56
2 2 1
2.已知2x -3x-2=0,求x + ——的值。
2
x
（是2x平方-3x-2=0，求x的平方+x的平方分之1的值）
3.若ab=1，则（1+a的平方分之1 + 1+b的平方分之1的值为多少，请自己那笔写，这上面不好打出来，谢谢大家帮忙！！！
(1)a(1/b+1/c)+b(1/c+1/a)+c(1/a+1/b)
=a/b+a/c+b/c+b/a+c/a+c/b
=(a+c)/b+(a+b)/c+(b+c)/a
a+b+c=0
(a+c)/b+(a+b)/c+(b+c)/a
=-b/b-c/c-a/a
=-3
(2)2x^2-3x-2=0
(2x+1)(x-2)=0
x1=-0.5,x2=2
x1=-0.5,x^2+1/x^2=4.25
x1=2,x^2+1/x^2=4.25
(3)1/(1+a^2)+1/(1+b^2)
=(1+b^2)/ (1+a^2)(1+b^2)+(1+a^2)/(1+a^2)(1+b^2)
=(2+a^2+b^2)/[a^2+b^2+(ab)^2+1]
=(2+a^2+b^2)/(a^2+b^2+2)
=1
(1)a(1/b+1/c)+b(1/c+1/a)+c(1/a+1/b)
=a/b+a/c+b/c+b/a+c/a+c/b
=(a+c)/b+(a+b)/c+(b+c)/a
a+b+c=0
(a+c)/b+(a+b)/c+(b+c)/a
=-b/b-c/c-a/a
=-3
(2)2x^2-3x-2=0
(2x+1)(x-2)=0
x1=-0.5,x2=2
x1=-0.5,x^2+1/x^2=4.25
x1=2,x^2+1/x^2=4.25
(3)1/(1+a^2)+1/(1+b^2)
=(1+b^2)/ (1+a^2)(1+b^2)+(1+a^2)/(1+a^2)(1+b^2)
=(2+a^2+b^2)/[a^2+b^2+(ab)^2+1]
=(2+a^2+b^2)/(a^2+b^2+2)
=1
(1)a(1/b+1/c)+b(1/c+1/a)+c(1/a+1/b)
=a/b+a/c+b/c+b/a+c/a+c/b
=(a+c)/b+(a+b)/c+(b+c)/a
a+b+c=0
(a+c)/b+(a+b)/c+(b+c)/a
=-b/b-c/c-a/a
=-3
(2)2x^2-3x-2=0
(2x+1)(x-2)=0
x1=-0.5,x2=2
x1=-0.5,x^2+1/x^2=4.25
x1=2,x^2+1/x^2=4.25
(3)1/(1+a^2)+1/(1+b^2)
=(1+b^2)/ (1+a^2)(1+b^2)+(1+a^2)/(1+a^2)(1+b^2)
=(2+a^2+b^2)/[a^2+b^2+(ab)^2+1]
=(2+a^2+b^2)/(a^2+b^2+2)
=1