已知x的三次方加y的三次方加4x减6y加13等于0,试求3x加y的值-搜答案-智慧作业帮

x+y=7x^2+y^2=55(x+y)^2=x^2+y^2+2xy=492xy=49-55=-6,xy=-3（x^3）·（y^3）=(xy）^3=(-3)^3=-27

X³+Y³=(X+Y)(X²-XY+Y²)

已知x+y=1,则x^3+y^3+3xy=（x+y）(x^2-xy+y^2)+3xy=1×(x^2-xy+y^2)+3xy=x^2-xy+y^2+3xy=x^2+2xy+y^2=(x+y)^2=1^2

见图

令2x平方加3x三次方加1为t,则y=cos三次方t令cost为a,则y=a的三次方.所以导数为3cos平方（2x平方加3x三次方加1）*{-sin（2x平方加3x三次方加1）}*（4x+9x的平方）

x^3y-2x^2y^2+xy^3=x^3y+2x^2y^2+xy^3-4x^2y^2=xy(x^2+2xy+y^2)-4x^2y^2=xy(x+y)^2-4x^2y^2=12×7×7-4×12×12

X2+Y2-4X-6Y+13=0X2-4X+4+Y2-6Y+9=0（X2-4X+4）+（Y2-6Y+9）=0（x-2）2 +（y-3）2=0所以,x-2=0 x=2y-

x³+x²y+xy²+y³=x²(x+y)+y²(x+y)=(x+y)(x²+y²)

已知A=x³+2y³-xy²,B=-y³+x³+2xy²,其中x等于1\3,y等于2A-B=（x³+2y³-xy

先分解因式,后乘法.(X^4-Y^4)/(X^3+X^2Y+XY^2+Y^3)=(X-Y)(X+Y)(X^2+Y^2)/(X^3+X^2Y+XY^2+Y^3)=(X-Y)(X^3+X^2Y+XY^2+

7x^3-6x^3y+3x^2y+3x^3+6x^3y-3x^2y-10x^3,其中x=-2010.y=2012=(7x^3+3x^3-10x^3)+(6x^3y-6x^3y)+(3x^2y-3x^2

x二次方加y的二次方减6x加4y加13的平方根等于零x^2+y^2-6x+4y+13=0x^2-6x+9+y^2+4y+4=0(x-3)^2+(y+2)^2=0x-3=0,y+2=0x=3,y=-2x

=xy(4x²+4xy+y²)=xy(2x+y)²

原式等于(xy)^2(x+y)将x+y=2,xy=4代入,得原式等于16×2=32

由x³+x²+x+1=0,可得x=0所以1+x+x²+x³+x^4=1+0=1或者变形：1+x+x²+x³+x^4=1+（1+x+x

x³-y³-x²y+xy²=(x³-y³)-(x²y-xy²)=(x-y)(x²+xy+y²)-xy

(x+y)^3=x^3+3x^2y+3y^2x+y^3

(x+y)(x^2-xy+y^2)

(x+y)^3=(x+y)^2*(x+y)=(x^2+2xy+y^2)(x+y)=x^3+3x^2y+3xy^2+y^3