已知x/(x^2-x+1)=7,求x^2/(x^4+x^2+1)的值.):∵x/(x^2-x+1)=7,∴x/x(x-1+1/x)=7,∴1/(x-1+1/x)=7,∴x-1+1/x=1/7,∴x+1/x=8/7,∴(x+1/x)^2=x^2+2+1/x^2=64/49∴x^2+1+1/x^2=15/49,∴x^2/(x^4+x^2+1)=x^2/x^2(x^2+1+1/x^2)=1/(x^2+1+1/x^2)=49/15,错处
来源:学生作业学帮网 编辑:学帮网 时间:2024/06/10 09:00:04
已知x/(x^2-x+1)=7,求x^2/(x^4+x^2+1)的值.):∵x/(x^2-x+1)=7,∴x/x(x-1+1/x)=7,∴1/(x-1+1/x)=7,∴x-1+1/x=1/7,∴x+1/x=8/7,∴(x+1/x)^2=x^2+2+1/x^2=64/49∴x^2+1+1/x^2=15/49,∴x^2/(x^4+x^2+1)=x^2/x^2(x^2+1+1/x^2)=1/(x^2+1+1/x^2)=49/15,错处:∴(x+1/x)^2=x^2+2+1/x^2=64/49∴x^2+1+1/x^2=15/49.未去分母的分式不能直接在分子上减1!我个人认为是错误的解法,请问这样解是不是错了!
你们都做错了
没错啊,兄弟,只不过你导了半天把结果又倒回去了!
其中
∵x/(x^2-x+1)=7,∴x/x(x-1+1/x)=7,∴1/(x-1+1/x)=7,∴x-1+1/x=1/7,∴x+1/x=8/7,∴(x+1/x)^2=x^2+2+1/x^2=64/49 {∴x^2+1+1/x^2=15/49,} ∴x^2/(x^4+x^2+1)=x^2/x^2(x^2+1+1/x^2)=1/(x^2+1+1/x^2)=49/15, .【∴x^2+1+1/x^2=15/49,】这不就又回去了么?
已知x=2π+1求 |x-1|+|x-2|+|x-3|+|x-4|+|x-5|+|x-6|+|x-7|+|x-8|+|x-9|+|x-10|
已知1+x+x^2+x^3=0,求x+x^2+x^3+x^4+x^+x^6+x^7+x^8的值
已知x=2π+1.求(X-1)+(X-2)+(X-3)+(X-4)+(X-5)+(X-6)+(X-7)+(X-8)+(X-9)+(X-10)
已知x*x+x-1=0 求x*x*x-2x+11=?
已知x*x+x-1=0求x*x*x-2x+2010的值
已知x+1/x=7 求x^2/x^4+x^2+1
一个“整式的乘法”的问题请先阅读下列解题过程,再仿做下面的问题.已知X*X + X - 1=0,求X*X*X + 2*X*X + 3的值.解X*X*X + 2X*X +3=X*X*X +X*X -X +X*X +X +3=X{X*X +X -1} +X*X +X -1 +4=0+0+4=4+ x + X*X + X*X*X=0.+ X*X + X*X*X
已知x*x-3x+1=0求√(x*x+1/x-2)=?
已知x+1/x=2,求(x^2008+ x^-2008 -2)/(x^2009 +x^-2009)
已知x^-x-1=0,求x^4+x^3-x^2-4x+3
已知x=1/x,求x^2-6x+9/x-3/x+3/x^2+6x+9
已知x+1/x=√7,求(1)x^2+1/x^2(2)x-1/x
已知,x+1/x=2,求,(x^2+2x+1)/(4x^2-7x+4)的值
已知x/x^2-x+1=7求x^2/x^4+x^2+1的值
已知x/(x^2-x+1)=7,求x^2/(x^4+x^2+1)的值.
已知:x+1/x=根号7,求x^2+1/x^2,x-1/x的值
已知x+1/x=2求x²+2x+1/4x²-7x+4
已知x+1/x=2求4x²-7x+4/x²+2x+1