已知x的平方加y的平方=2,x y=1
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把25拆成16+9(x²-8x+16)+(y²+6y+9)=0(x-4)²+(y+3)²=0平方大于等于0,相加等于0若有一个大于0,则另一个小于0,不成立.所
A+B=2x²-3xy+y²+x²+2xy-3y²=3x²-xy-2y²A-2B=2x²-3xy+y²-2(x²
1.x^2+y^2=(x+y)^2-2xy=4-1=3(x-y)^2=(x+y)^2-4xy=4-2=22.(a+b)^2=7a^2+b^2+2ab=71式(a-b)^2=3a^2+b^2-2ab=3
x^2+y^2=6y-4x-13x^2+4x+4+y^2-6y+9=0(x+2)^2+(y-3)^2=0x=-2y=3x^2-y^2=(-2)^2-3^2=4-9=-5
(x-y)²=x²+y²-2xy=x²+y²+2xy-4xy=(x+y)²-4xy=7²-2[(x+y)²-x²
x²+2x+1+y²-6y+9=0(x+1)²+(y-3)²=0∴x+1=0y-3=0∴x=-1y=3
答:x²+y²-2x+8y+17=0(x²-2x+1)+(y²+8y+16)=0(x-1)²+(y+4)²=0所以:x-1=0y+4=0解得
x²-y²=(x²+xy)-(xy+y²)=3-(-2)=5再问:那么x的平方加4xy加3y的平方=2x的平方减xy减3y的平方=再答:x的平方加4xy加3y的
x方+y方+5/4=2x+y(x方-2x+1)+(y方-y+1/4)=0(x-1)方+(y-1/2)方=0x=1,y=1/2xy/(x+y)=1/3
(x平方+y平方)平方-y平方=x平方+6所以(x²+y²)²-(x²+y²)-6=0(x²+y²+2)(x²+y
问题求什么?再问:求x加y的值再答:x^2-2x+1+y^2-6y+9=0(x-1)^2+(y-3)^2=0x=1y=32x+3y=11
x²-2x+y²+6y+10=0(x²-2x+1)+(y²+6y+9)=0(x-1)²+(y+3)²=0∴x-1=0,y+3=0∴x=1,y
x^2+4x+y^2-2y+5=0(x^2+4x+4)+(y^2-2y+1)=0(x+2)^2+(y-1)^2=0x=-2,y=1x^2+y^2=(-2)^2+1^2=4+1=5
由x+y=25x+y=7则(x+y)=x+y+2xy=7=492xy=(x+y)-(x+y)=49-25=24则(x-y)=x+y-2xy=25-24=1因为:x<y所以x-y<0即x-y=-1
x的平方加y的平方加2x-6y+10=0即:(x+1)^2+(y-3)^2=0所以:x=-1,y=3.所以:x+y=2.
由题意可得x²+y²+2x+6y+10=0(x+1)²+(y+3)²=0所以x=-1,y=-3
把X的平方加Y的平方设成W,然后计算我相信你会的...设(X的平方+Y得平方)=W原式可得:WX(W-2)=15解得W=-3或者W=5但是因为W=X的平方+Y的平方,故W不为负数,所以W=-3舍去所以