x方-3x-4＝0-搜答案-神马作文网

因为3x方+xy-2y方=0,即（x+y)(3x-2y)=0,而x+y≠0,所以3x-2y=0原式=[（x+y)^2-4xy]/[(x+3y)(x-y)/(x+3y)(x-3y)=(x-3y)/(x+

依次为：(x-3)(x+1)；(x+9)(x-2)；(x-4)(x+1)；(x+6)(x-1)；(x-4)(x-9)；(2x+1)(x+1)

6x^2-7x+1=0(6x-1)(x-1)=0x1=1/6;x2=15x方-18=9x变为5x^2-9x-18=0(5x+6)(x-3)=0x1=-6/5;x2=34x^2-3x=52变为4x^2-

即(3x-4y)(x+y)=03x=4y或x=-y若3x=4yy=3x/4则y²=9x²/16,xy=3x²/4原式=(3x²/4-3x²)/(9x&

1、2x^4y^3-x^2y=2x(xy)^3-(xy)x=54x-3x=51x已知2x-y=4,xy=3,可求得x值代入即可.

把X方—3X+1=0两边除以X得X-3+x分之一=0,x+x分之一=3,变成x方分之一+2+x方=3,变成x方分之一+x方=1,

4x方+x+2x根号下(3x方+x)=[x+根号下(3x方+x)]的平方=9x+根号下(3x方+x)=33x方+x=(3-x)的平方=9-6x+x方2x方+7x=9x=1

x²-2x+3=0x²-2x=-3所以原式=2(x²-2x)-20=-6-20=-26

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先转化到2个未知数用另外一个未知数表示,然后代入求值4x-3y-6z=0x+2y-7z=0解得x=3zy=2z（2x²+3y²+6z²)/(x²+5y²

(1)6x^2-7x+1=0(x-1)(6x-1)=0所以x1=1,x2=1/6(2)5x^2-18=9x5x^2-9x-18=0(5x+6)(x-3)=0所以x1=-6/5,x2=3(3)4x^2-

x方+y方-4x+y+4分之17＝0x²-4x+4+y²+y+1/4=0(x-2)²+(y+1/2)²=0由非负性x-2=0y+1/2=0解得x=2y=-1/2

一、2x^2-3x-2/3=0△=(-3)^2-4*2*(-2/3)=9+16/3=43/3>0所以方程有两个不相等的实数根二、16x^2-24x+9=0△=(-24)^2-4*16*9=576-57

像这种题目也可以用特殊值去做,比如令x=1,代入方程求出y,再代入所求的式子就可以得出答案.

x(x-1)(x-2)³(x+1)(x-1)(x-1)(x²+x+1)/[(3-4x)(x²+x+2)]>0x(x-1)³(x-2)³(x+1)(x&

（1）x²+x=0x(x+1)=0x1=0x2=-1(2)x²-2√3x=0x(x-2√3)=0x1=0x2=2√3(3)4x²-121=0(2x+11)(2x-11)=

x二次方-x-4分之3=0

"x2-x+1/4-1/4-3/4=0（x-1/2）2-1=0x-1/2=1或x-1/2=-1x=3/2或x=-1/2"

x^3-3x^2+4=0x^3-2x^2-(x^2-4)=0x^2(x-2)-(x+2)(x-2)=0(x-2)（x^2-x-2）=0（x-2）^2(x+1)=0x=2-1

两边乘-1(x²-3x+2)(x²-2x-3)>0(x-1)(x-2)(x-3)(x+1)>0零点是-1,1,2,3由穿针法x

17x的9次方,上式为2x的9次方-64x的9次方+81x的9次方