已知x的平方加y的平方等于6
来源:学生作业帮助网 编辑:作业帮 时间:2024/05/17 22:00:57
应该是x^2-2x+y^2+6y+10=0配方:x^2-2x+1+y^2+6y+9=0(x-1)^2+(y+3)^2=0得x=1y=-3所以x+y=-2
x^2-2x+y^2+6y+10=0(x-1)^2+(y+3)^2=0(x-1)^2=0x-1=0x=1(y+3)^2=0y+3=0y=-3x+y=1-3=-2
x²-y²=6y=-x+3代入x²-(-x+3)²=6x²-x²+6x-9=66x=15所以x=5/2y=-x+3=1/2
X²+Y²=10..(1)X+Y=6..(2)(2)²-(1)得2XY=26XY=13如果认为讲解不够清楚,
x^2+2x+y^2-6y+10=0=(x^2+2x+1)+(y^2-6y+9)=0=(x+1)^2+(y^2-6y+3^2)=0=(x+1)^2+(y-3)^2=0x=-1y=3xy=-3
x^2+y^2-6x+4y+13=0(x-3)^2+(y+2)^2=0所以x=3y=-2x^y=3^(-2)=1/9
x^2-2x+y^2+6y+10=0x^2-2x+1+y^2+6y+9=0(x-1)^2+(y+3)^2=0x-1=0,y+3=0x=1,y=-3(x-y)/(x+y)=4/(-2)=-2
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
把34拆成9+25(x²+6x+9)+(y²-10y+25)=0(x+3)²+(y-5)²=0平方大于等于0,相加为0则只有都等于0所以x+3=0,y-5=0x
(x+y)²=20,∴x²+y²+2xy=20(x-y)²=40,∴x²+y²-2xy=40两个式子相交得2(x²+y²
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
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+y)平方=x平方+2xy+y平方=13(x-y)平方=x平方-2xy+y平方=9两式相加得2(x平方+y平方)=22,x平方+y平方=11两式相减得4xy=4,xy=1
根据(x+y)2=x2+y2+2xy,可得x2+y2=13
解题思路:(x+y)的平方+|y—3|=0则x+y=0,y-3=0即x=-3,y=3解题过程:
∵x的平方加xy等于负5,xy加y的平方等于9∴x的平方减y的平方=(x²+xy)-(xy+y²)=-5-9=-142x的平方加3xy加y的平方=2(x²+xy)+(xy