先化简再求值(5y 1)(5y-1)

k=3＞0,y随x的增大而增大∵－5＜－2∴y2＜y1

可得函数的对称轴为：x=2所以可得当x=-1时与x=5的函数值相同,3>0所以当x

【(x+2y)^2-(x+y)(3x-y)-5y^2】/(2x)=(x^2+4xy^2+4y^2-3x^2-2xy+y^2-5y^2)/(2x)=(-2x^2+4xy^2-2xy)/(2x)=-x+2

因为：一次函数y=-1/3x+2过点(-5,y1),(3,y2)所以：y1=-1/3×（-5）+2；y2=-1/3×3+2=5/3+2=（-1）+2=11/3=1即：y1=11/3；y2=1所以：y1

[(x+2y)(x-2y)-(x+4y)²]÷4y=(x²-4y²-x²-8xy-16y²)÷4y=(-20y²-8xy)÷4y=-5y-2

先化简再求值4x^5y³÷{x^4y³÷[x³y÷（x³y²÷2xy²)]}=4x^5y³÷{x^4y³÷[x³

代x=-5入y=3X-2则：y1=3×（-5）-2=-17代x=-2入y=3X-2则：y2=3×（-2）-2=-8∵-17＜-18∴y1＜y2直线y=X+3与Y轴的交点坐标为?与X轴的交点坐标?当x=

分别将点A(-13/4,y1),B(-5/4,y2),C(1/4,y3)代入y=x²-mx+n上得：y1=(-13/4)²-m(-13/4)+n=169/16+13m/4+ny2=

x²-4y²分之x+2y=[(x-2y)(x+2y)]分之x+2y=x-2y分之1=5-2*3.5=-2

X-(Y-2X+(3X-2(2X+Y)+5Y))=X-(Y-2X+(3X-4X-2Y+5Y))=X-(Y-2X+(-X+3Y))=X-(Y+3Y-2X-X)=X-4Y+3X=4X-4Y当X-Y=2X-

5x-{2y-3x+[5x-2(y-2x)+3y]}=5x-[2y-3x+(5x-2y+4x+3y)]=5x-[2y-3x+(9x+y)]=5x-(2y-3x+9x+y)=5x-(3y+6x)=5x-

x^2-4x+y^2+2y+5=0.(x-2)^2+(y+1)^2=0x=2y=-1：（2x+y)(2x-y)-(-2x+y)^2,=4x^2-y^2-4x^2-y^2+4xy=4xy=4*2*1=8

[（x+2y）²-（x+y)(3x-y)-5y²]÷（2x）,=(x²+4xy+4y²-3x²-2xy+y²-5y²)/(2x)=

解(x-y)(x+y)-(x-2y)²+x(3x-5y)-(x-y)(x-2y)=(x²-y²)-(x²-4xy+4y²)+(3x²-5xy

3x-5y=03x=5yx/y=5/3(x-2y)/(x+3y)=(x/y-2y/y)/(x/y+3y/y)=(x/y-2)/(x/y+3)=(5/3-2)/(5/3+3)=(-1/3)/(14/3)

X平方+Y平方-2X+4Y+5=0=>(x-1)^2+(y+2)^2=0=>x=1,y=-2（2x+y）（2x+y)-(2x-y)平方=8xy=-16

（x-y）（x-2y）-1/2（2x-3y）（x+2y）,其中x=2,y=2/5=x²-3xy+2y²-1/2(2x²+xy-6y²)=x²-3xy+

(3x-y)^2-(2x+y)^2-5x(x-y)=(3x-y+2x+y)(3x-y-2x-y)-5x(x-y)=5x*(x-2y)-5x(x-y)=5x^2-10xy-5x^2+5xy=-5xy=-

(3x+2y)(4x+5y)+(2x)^2*(3y)^3/36x^2y+5xy=12x^2+23xy+10y^2+4x^2*27y^3/36x^2y+5xy=12x^2+28xy+10y^2+3y^2

（2x-3y）^2-（x-2y）（x-5y）-（2x+y）（2x-y）=4x^2+9y^2-12xy-(x^2-2yx-5yx+10y^2)-(4x^2-y^2)=4x^2+9y^2-12xy-x^2