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3x+2﹣2x+1 3x+2﹣4x+1 3x+2﹣4x﹣2 3x+2﹣4x+2
X1 X2 (X1,X2) (X1,X2,X3,X4)
)(x+2)(x–2)=x2-4( )x2-4+3x=(x+2)(x–2)+3x ( )x2-3x-4=(x-4)(x+1)( )x2+2x-3=(x+1)2-4
(2x-2)(3x-4)=0,∴2-2x=0或3x-4=0 (x+3)(x-1)=1,∴x+3=0或x-1=1 (x-2)(x-3)=2×3,∴x-2=2或x-3=3 x(x+2)=0,∴x+2=0
2x-4-12x+3=9,-10x=9-4+3,故x=0.8 ; 2x-4-12x+3=9,-10x=9+4-3,故x=-1 ; 2x-4-12x-3=9,-10x=9+4+3,故x=-1.6; 2x-2-12x+1=9,-10x=9+2-1,故x=-1 ;
X1X2,X2X4 X1X2X3,X1X3X4,X2X4 X1X2X4 X1X3,X2X3X4
x1=﹣1,x2=﹣4 x1=1,x2=4 x1=﹣1,x2=4 x1=2,x2=3
X1 X2 (X1,X2) (X1,X2,X3,X4)
={x|x2-2x-3<0}, ={x|1≤x≤4},则A.∩B.= ( ) A.{x|1≤x<3} B.{x|1≤x≤3} {x|3{x|3≤x≤4}
4-x2+3x=(2-x)(2+x)+3x -x2+3x+4=-(x+4)(x-1) 1-4x+4x2=(1-2x)2 x2y-xy+x3y=x(xy-y+x2y)
X1.X2.X5 X1.X3.X4 X1.X2.X4 X1.X3.X5
X1 X2 (X1,X2) (X1,X2,X3,X4)
4x+3x=1-2 4x-3x=-2-1 4x-3x=2-1 4x+3x=-2-1
X1X2,X2X4 X1X2X3,X1X3X4,X2X4 X1X2X4 X1X3,X2X3X4
3x﹣(2x﹣1)=3x﹣2x﹣1 ﹣4(x+1)+5=﹣4x+4+5 2x+7(x﹣1)=2x+7x﹣1 2﹣[3x﹣5(x+1)]=2﹣3x+5x+5
x x≤3或x>4 x -1x 3≤x<4 x -2≤x<-1
(x-1)(x-2)=x2-3x+2 x2-3x+2=(x-1)(x-2) x2+4x+4=x(x一4)+4 x2+y2=(x+y)(x―y)