x 2.1=3befachengji-搜答案-百度作业网

1/10x4+3x2+1=x4-x3+(x3+3x2+x)-x+1=x4-x3+x(x2+3x+1)-x+1=x4-x3-x+1=x4-(x3+3x2+x)+3x2+1=x4-x(x2+3x+1)+3

An=(2n-1)x2^n=nx2^(n+1)-2^n,则Sn=[nx2^2x(2^n-1)/(2-1)]-[2x(2^n-1)/2-1]=(2^n-1)(4n-1)

设(x²-1)/(x²+2x)=t则8t+3/t=118t²-11t+3=0(8t-3)(t-1)=0解得t=3/8或t=11.t=3/8(x²-1)/(x&#

后面的x²＋11x－708有误吧!再问：没有题目就这样能不能帮我再答：那我就试试：原式为：1/x2+x+1/x2+3x+2+1/x2+5x+6+1/x2+7x+12+1/x2+9x+20=5

x2+3x2+1=0中的3x2表示什么?再问：已知X2+3X+1=0，求X2+1/X2的值？得数是7。求过程？我打的是X的平方。怎么会出X2、再答：答：因为x≠0,两边都除以x得：x+1/x=-3，两

3/x2=1/x2-x,解方程

3/x2=1/x2-x即3*2-3x=x*22x*2=3Xx=0（舍去）x=3/2

1/(x²+3x+2)=[(x+2)-(x+1)]/(x+1)(x+2)=1/(x+1)-1/(x+2)同理1/(x²+5x+6)=1/(x+2)-1/(x+3)1/(x²

原式可化为1/(x+1)(x-3)+2/(x-3)((x+2)+3/(x+1)(x+2)=0两边同乘以：(x+1)(x+2)(x-3)得：(x+2)+2(x+1)+3(x-3)=0(x≠-1,x≠-2

x2-5x+1=0则x2+x2/1

你可以参见“韦达定理”方程两个根的积是1,说明他们互为倒数.x^2+1/x^2=(x+1/x)^2-2*x*1/x=（-5）²-2=23

x^2+3x+1=0方程两边同除以xx+3+1/x=0x+1/x=-3x^2+1/x^2=(x+1/x)^2-2=(-3)^2-2=9-2=7

把x2-1x2+2x=y代入原方程，得：8y+3y=11．方程两边同乘以y得：3y2-11y+8=0．故选A．

x/x²-3x+1=1/5x²-3x+1=5xx²+1=8xx+1/x=8平方x²+2+1/x²=64x²+1/x²=62x

Sn=1*2+3*2^2+5*2^3+……+(2n-1)*2^n2Sn=1*2^2+3*2^3+...+(2n-1)*2^(n+1)相减得-Sn=1*2+2*2^2+2*2^3+..+2*2^n-(2

7/（x+x2）-3/（x-x2）=6/（x2-1）两边同乘以x(x+1)(x-1),得7(x-1)+3(x+1)=6x7x-7+3x+3=6x10x-6x=3-74x=-4x=-1经检验x=-1是增

两边乘x(x+1)(x-1)2(x-1)+3(x+1)=4x2x-2+3x+3=4x5x+1=4xx=-1经检验,x=-1时分母x+1=0增根,舍去方程无解

x²+x-1/(x²+x)=3/2两边同时乘以(x²+x)得：(x²+x)²-1=3(x²+x)/22(x²+x)²-3

x/(x²-3x+1)=2(x²-3x+1)/x=1/2翻过来x+1/x=7/2(x^4+x2+1)/x²翻过来=x²+2+1/x²=(x+1/x)&

原式=2x2-1，当x=-3时，原式=2×（-3）2-1=17．

x1³+x2³=(x1+x2)(x1²-x1*x2+x2²)=(x1+x2)[(x1+x2)²-3x1*x2]=3×(3²-3×1)=3×6

X2-3X-1=0则X-3-1/X=0则X-1/X=3则(X-1/X)²=3²=9则X²-2+1/X²=9则X²+1/X²=9+2=11