若实数xy满足x方加y方减一等于零2-搜答案-搜搜考试网

见图

k=(y+2)/(x+1)所以k就是过点(-1,-2)的直线的斜率x,y满足x^2+y^2=1所以就是求过点(-1,-2)的直线和单位圆有公共点是斜率的取值范围显然相切时有最值y+2=kx+kkx-y

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

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

再问：图片看不全再答：能看到了吧？

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+

2x²=x²+x²所以(x²-2xy+y²)+(x²+2x+1)=0(x-y)²+(x+1)²=0平方大于等于0,相加等

1/(x^4)+4/(y^4)xy=1,所以y=1/x即y^4=1/（x^4）代入原式,得到1/(x^4)+4(x^4)再由重要不等式,得到1/(x^4)+4(x^4)≥2(根号)1/(x^4)·4(

x^2+x=1x^3+x^2=x(x^2+x)=x原式x^2+1/x=1/x(x^3+1)=1/x(x^3+x^2+x)=1/x*2x=2

首先x3-y3=(x-y)(x2+xy+y2)其次x3-y3-3xy=1所以x3-y3=1+3xy=(x-y)(x2+xy+y2)x-y=(1+3xy)/(x2+xy+y2)=(1+3xy)/[(x-

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]/

（x^2+y^2）*(x^2-1+y^2)-12=0可以设x^2+y^2=z那么有z(z-1)=12z^2-z-12=0(z-4)(z+3)=0z=4或z=-3但z是平方和一定大于0所以z=4记得采纳

x²+2xy-3y²=0(x+3y)(x-y)=0解得x=y或x=-3y又x,y为正数所以y=x；x=-3y舍(x²+xy+y²)/(x²-xy+y&

第一题：设3^x=y,这里3^x表示3的x次方的意思那么原式变为y^2-8y-9=0,这个就简单了,解得y=-9或者y=1由于y=3^x,只能是3的整数次幂,所以y不能是-9,所以y=1那么3^x=1

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

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方-4XY+4Y方-6X+9=0(x^2-4xy+4y^2)+(x^2-6x+9)=0(x-2y)^2+(x-3)^2=0所以有x-2y=0,x-3=0即有x=3,y=x/2=3/2x*根号8Y=

原式=2x²-4xy+2y²-7y²=(√2x-√2y)²-7y²=(√2x-√2y+√7y)(√2x-√2y-√7y)