已知x方加2y方加z方减2xy减2y减4z加五等于n-搜答案-智慧作业帮

由（1）x²-xy=5（2）y²+xy=-2∴（1）+（2）得：x²+y²=3.

见图

3x^2+2xy+y^2-6x-6y+9=0(x+y)^2-6(x+y)+9=0(x+y-3)^2=0x+y=3

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

14=1+4+9所以(x²-2x+1)+(y²+4y+4)+(z²+6z+9)=0(x-1)²+(y+2)²+(z+3)²=0平方大于等于0

x²＋xy－2y²＝0﹙x－y﹚﹙x＋2y﹚＝0x＝y,x＝－2y当x＝y,﹙x²＋3xy＋y²﹚／﹙x²＋y²﹚=﹙y²＋3y&

很高兴喂你解答!原式=4√[(x^2+xy+y^2)/(x-y)*1/2√[(x^2-xy+y^2)/(x+y)*3√(x^3+y^3)=6√[(x^2+xy+y^2)/(x-y)*√[(x^2-xy

x⁴-2y⁴-2x³y+xy³=(x+y)(x-2y)(x²-xy+y²)

再问：图片看不全再答：能看到了吧？

x/y=3x=3y原式=[(3y)²+2*3y*y-3y²]/[(3y)²-3y*y+y²]=(9y²+6y²-3y²)/(9y&

x²+2xy+4y²+x²y²+1=8xy(x²-4xy+4y²)+(x²y²-2xy+1)=0(x-2y)²

已知x=二分之一,xy(y加y的二次方)减y的二次方(xy-x)+2x(x-y的平方)的值=xy²+xy³-xy³+xy²+2x²-2xy²

已知:(x-1)(y-2)-x(y-3)=8,那么：xy-2x-y+2-xy+3x=8化简得：x-y=6所以：2分之(x²+y²）-xy=2分之(x²+y²-2

x^2+y^2=4,设x=2cosa,y=2sina,则x^2-2√3xy-y^2=4(cosa)^2-8√3cosasina-4(sina)^2=4cos2a-4√3sin2a=8cos(2a+60

(x＋y)/(x)=31＋(y/x)=3得：y/x=2则：(x²＋y²)/(x²－xy＋y²)【分子分母同除以x²】=[1＋(y/x)²]/

x³y³－2x²y²＋xy＝xy（x²y²－2xy＋1）＝xy（xy－1）²

(x-y)^2=x^2+y^2-2xyx^2+y^2=(x-y)^2+2xy=5^2+2*2=25+4=29再问：能再简单点吗？再答：x^2+y^2=(x-y)^2+2xy=5^2+2*2=25+4=

X方加2XY加2Y方减4Y加5=(X²+2XY+Y²)+(Y²-4Y+4)+1=(X+Y)²+(Y-2)²+1当Y=2,X=-2时,原式的值最小,为1

2x^2+xy-y^2-4x+5y-6双十字相乘法,2x^2+xy-y^2-4x+5y-62x-y2xy-3（2x-y+2)(x+y-3)或者待定系数法.有问题追问再问：谢谢谢谢谢谢谢你再答：不用谢