x2-y2=24,x y=6,求代数式5x 3y
来源:学生作业帮助网 编辑:作业帮 时间:2024/09/22 07:03:19
∵x2+y2-4x+6y+13=(x-2)2+(y+3)2=0,∴x-2=0,y+3=0,即x=2,y=-3,则原式=(x-3y)2=112=121.
x2-xy=-3①,2xy-y2=-8②,①×2+②×3得:2x2-2xy+6xy-3y2=-6-24=-30,则2x2+4xy-3y2=-30.
X2+Y2+8X+6Y+25=0x²+8x+16+y²+6y+9=0(x+4)²+(y+3)²=0∴x+4=0y+3=0x=-4y=-3X2+4XY+4Y2分之
X2+Y2+8X+6Y+25=0x^2+y^2+8x+6y+25=0x^2+8x+16+y^2+6y+9=0(X+4)^2+(y+3)^2=0x=-4y=-3(x^2-4y^2)/(x^2+4xy+4
∵x2+xy=-3,xy+y2=7,∴(x2+xy)+(xy+y2)=-3+7=4,即x2+2xy+y2=4.
x2-y2=(x2-xy)+(xy-y2)=21-12=9;x2-2xy+y2=(x2-xy)-(xy-y2)=21+12=33.
5x2—3xy—4y2—11xy—7x2+2y2=-2x2-2y2-14xy=-2(x2+y2)-14xy=-14+28=14
x+y=7xy=27^2=(x+y)^2=x^2+2xy+y^2=x^2+y^2+2*2x^2+y^2=45(1)y=7-xx(7-x)=2x^2-7x+2=0x=(7+41^(1/2))/2或x=(
你好x²+y²-10x-6y+34=0(x-5)²+(y-3)²=0每项都大于等于0,只有等于0时上式才成立,所以x=5y=3(x-y/x+y)²÷(
再问:你确定吗?再答:我保证再答:亲,那一步不明白可以问再问:你省略了一步吧!再答:能看明白吗再问:no再答: 再答:是不是这部再问:那么第一步是怎么得来的呢?再答:第一步不是你
已知2x=3y,求xy/(x^2+y^2)-y^2/(x^2-y^2)的值2x=3y-->x=(3/2)yx^2=(9/4)y^2xy/(x^2+y^2)-y^2/(x^2-y^2)==(3/2)y*
是求x2/y2+y2/x2=吗x2-y2=xy则x/y-y/x=1两边平方得x^2/y^2-2+y^2/x^2=1所以x^2/y^2+y^2/x^2=3
X2+xy-(xy+y2)=4-12x2+xy-xy-y2=-8x2-y2=-8x2+xy+xy+y2=4+12x2+2xy+y2=16
10拆成1+9X2-2X+1+Y2-6Y+9=0(X-1)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.所以两个都等于0所以X-1=0,Y-3=0X=1,Y=
x²-2x+y²+6y+10=0,变换得(x-1)²+(y+3)²=0,∴x=1,y=-3∴(x2-2xy)/(xy+y2)=(1²-2*(-3))/
条件变换:(x-3)^2+(y+1)^2=0即:y+1=0x-3=0所以:立方根号x2-y2=2
x^2+xy+y^2=2≥3xyxy≤2/3-2xy≥-4/3,x^2-xy+y^2=x^2+xy+y^2-2xy=2-2xy≥2/3当且仅当x=y时取等号再问:>=2/3且
x2+2xy-3y2=x2-xy+3xy-3y2=x2-xy+3(xy-y2),∵x2-xy=3,xy-y2=-5,∴x2+2xy-3y2=3+3×(-5)=-12.
∵4x2+8xy+9y2=4x2+2xy+9y2+6xy=2(2x2+xy)+3(3y2+2xy),2x2+xy=6,3y2+2xy=9,∴2(2x2+xy)+3(3y2+2xy)=2×6+3×9=3
因为x²+4y²+x²y²-6xy+1=0(x²-4xy+4y²)+(x²y²-2xy+1)=0(x-2y)²