如果方程组{3x y=2k 3 x 3y=5
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y=3x^2-8,代入第2个方程得:x^2+x(3x^2-8)+3x^2-8=43x^3+4x^2-8x-12=0解得只有一个实根:x=1.67758093466546故y=0.442833377再问
四个方程标好号(3)×3-(1)得x=4把x=4代入(3)得∴4-y=1∴y=3把x=4,y=3分别代入(2)(4)得4a+3b=1(5)4b+3a=6(6)解这个方程组得a=-2b=3∴(a+b)的
x^2-2xy-3y^2=0(x-y)^2-4y^2=0(x-y)^2=(2y)^2x-y=±2yx-y=2y或x-y=-2yx1=3yx2=-y将x1,x2分别代入②,得:(3y)^2-y*3y+y
解出x=(7k-4)/5y=(-8k+11)/5由x>yk>1
xy/(2x+y)-xy/(2x-y)=3xy/(2x-y)+xy/(2x+y)=4;一、两公式对加得2xy/(2x+y)=7xy=(2x+y)*7/2二、把xy代入原公式求解就行了:(2x+y)*7
x+y=2-a(1)4x+5y=3-6a(2)(2)-4*(1)得,y=3-6a-4(2-a)y=-2a-5代入(1)得,x-2a-5=2-ax=a+7x>0,y>0a+7>0,a>-7-2a-5>0
由xy=3得:y=3/x代人①得:3x+6/x=9整理得到:x²-3x+2=0,解得:x1=1x2=2∴y1=3y2=3/2
(xyz)2=12(xy)2=4(yz)2=9(xz)2=4所以X2=12/9x=±(2/3)√3y2=12/4y=±√3z2=12/4z=±√3xyz同号所以x=(2/3)√3y=√3z=√3x=-
解1式:(x+4y)(x-y)=0x=-4y时,解2式得:x=-10/3,y=5/6;x=10/3,y=-5/6x=y时,解2式得:x=5,y=5;x=-5,y=-5
x²-2xy+y²=12x²-5xy-3y²=0即(x-y)²=1(2x+y)(x-3y)=02x+y=0或x-3y=0如果2x+y=0,则y=-2x
xy/3x+2y=1/8,xy/2x+3y=1/73x+2y/xy=8,2x+3y/xy=73/y+2/x=8,2/y+3/x=73/y+2/x=8,2/y+3/x=71/x=1,1/y=2,x=1,
x+y=-3x=-3-y带入xy=2(-3-y)y=2-y^2-3y-2=0y^2+3y+2=0(y+1)(y+2)=0y1=-1y2=-2x1=-2x2=-1
4x-3y=7,[(k+1)/2]x-y=k-3.8x-6y=14,3(k+1)x-6y=6k-18.二式减一式等于:(3k-5)x=6k-32,x=(6k-32)/(3k-5)有得:y=(3k-27
x=2,y=0.5
由2x²-3xy-2y²=0得2-3(y/x)-2(y/x)²=0(2+y/x)*(1-2y/x)=0得y/x=1/2或-2即y=1/2x或y=-2x代入x²+
将x,y的值代入ax-3y=5,得a/2-3(-2)=5a/2=5-6a=-2将x,y的值代入2x+by=1,得1+b(-2)=1b=0所以a+b=-2
由(x-2)(y+3)=xy(x-5)(y+2)=xy得3x-2y-6=02x-5y-10=0上面方程化为6x-4y-12=06x-15y-30=0两式相减得11y=-18,y=-18/11,代入任意
x^2-xy+y^2=3,2x^2-xy-y^2=55x^2-5xy+5y^2=156x^2-3xy-3y^2=15两式子相减x^2+2xy-8y^2=0(x+4y)(x-2y)=0x=2y或者x=-
x+y=mx=m-y代入xy=3得(m-y)y=3y^2-my+3=0有实根,则△=m^2-12≥0m≥2√3或m≤-2√3