下列方程的解分别是:
(1)x3-3x2+2x=0______.
(2)x4-5x2+4=0______.
(3)(x2-3x)2-2(x2-3x)-8=0______.
(4)(x2-5x-6)(x2-5x+11)=18______.
(5)(x+1)(x+2)(x-3)(x-4)=36______.
(6)(x+1)(x-1)=1______.
(7)x2-3|x|+2=0______.
(8)(x+1)(x-1)=x+1______.
(9)x2-3|x|+2=0______.
(10)x4+2x3+5x2+4x-12=0______.
网友回答
解:(1)x3-3x2+2x=0,∴x(x2-3x+2)=0,∴x1=0,x2=1,x3=2;
(2)x4-5x2+4=0,∴(x2-4)(x2-1)=0,∴x1=2,x2=-2,x3=1,x4=1;
(3)(x2-3x)2-2(x2-3x)-8=0,设x2-3x=y,
∴y2-2y-8=0,∴(y-4)(y+2)=0,∴x1=4,x2=-1,x3=1,x4=2;
(4)∵(x2-5x)2+5(x2-5x)-66=18,
∴(x2-5x)2+5(x2-5x)-84=0,(x2-5x+12)(x2-5x-7)=0
∴x2-5x+12=0(无解),或x2-5x-7=0,
它的解为x1=;
(5)∵(x2-2x-3)(x2-2x-8)=36,
∴(x2-2x)2-11(x2-2x)-12=0,
∴(x2-2x-12)(x2-2x+1)=0,
∴x2-2x-12=0或x2-2x+1=0,
∴
(6)(x+1)(x-1)=1∴x1,2=;
(7)x2-3|x|+2=0,当x>0时,x1=1,x2=2;当x≤0时,x1=-1,x2=-2;
(8)x2(x-2)-4(x-2)=0,(x-2)(x2-4)=0,(x-2)2(x+2)=0,
∴x1=x2=2,x3=-2
(9)∵x2=|x2|=|x?x|=|x||x|=|x|2,∴原方程为|x|2-3|x|+2=0,∴(|x|-1)(|x|-2)=0,∴|x|-1=0或|x|=2,∴x1=1,x2=-1,x3=2,x4=-2.
(10)∵(x4+2x3+x2)+(4x2+4x)-12=0.
即(x2+x)2+4(x2+x)-12=0,∴(x2+x+6)(x2+x-2)=0,∵
解析分析:(1)先分解因式再求解即可;
(2)分解因式再求解;
(3)先分解因式再求解即可;
(4)换元法即可求解;
(5)换元法即可求解;
(6)根据平方差公式即可求解;
(7)先分类讨论去绝对值即可求解;
(8)根据平方差公式即可求解;
(9)先分类讨论去绝对值即可求解;
(10)分解因式后即可求解;
点评:本题考查了高次方程,难度一般,关键是注意细心运算即可.