已知3xy-2x-2y 1=0求x y的最大值
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y1=y2可得:2x平方-3x+1=4x平方+4x+7移项并合并同类项得:2x平方+7x+6=0分解因式得(x=2)(2x+3)=0可得x1=-2;x2=-3/2所以可知x=-2或-3/2时,y1=y
X﹥1【解】∵y1>y2∴3x+3>-2x+8∴5x>5得x>1
3x*+xy-2y*=0(3x-2y)(x+y)=0那么x=2y/3或x=-yy/x=3/2或x/y=-1(x/y)-(y/x)-(x*+y*)/(xy)=(x/y)-(y/x)-(x/y+y/x)=
由y=3xy+x得x-y=-3xy2x+5xy-2y/x-2xy-y=2(x-y)+5xy/x-y-2xy=-6xy+5xy/-3xy-2xy1/5
y-x-2xy=0y-x=2xyx-y=-2xy(3x+xy-3y)/(y-xy-x)=[3(x-y)+xy]/[(y-x)-xy]=(-6xy+xy)/(2xy-xy)=-5xy/xy=-5
-xy(x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10
直接降维呗y2=y1*u=xcosxuy'=(cosx-xsinx)u+xcosxu'y''=(-sinx-sinx-xcosx)u+(cosx-xsinx)u'+(cosx-xsinx)u'+xco
解y2=2/y1=2/2x=1/xy2=2/y2=2/(1/x)=2xy3=2/y2=2/2x=1/xy4=2/y3=2/(1/x)=2x.不难发现yn是周期为2的数列y2006=y2=1/xy1*y
解(x+1)平方+/y-1/=0∴x+1=0,y-1=0∴x=-1,y=1∴2(xy-5xy平方)-(3xy平方-xy)=(2xy+xy)+(-10xy平方-3xy平方)=3xy-13xy平方=3×(
答案是3/2你是不是把分母打错了教你个方法因为上下是齐次的直接令x=3y=2带入就行
y1比y2大3,即:y1=y2+3y1=2(3x+4),y2=5(2x-7),2(3x+4)=5(2x-7)+36x+8=10x-35+38+35-3=(10-6)x40=4xx=10所以,当x为10
y-x-2xy=0所以x-y=-2xyy-x=2xy所以原式=[3(x-y)+xy]\[(y-x)-xy]=[3×(-2xy)+xy]\(2xy-xy)=-5xy\xy=-5
x²-10x+25+|y-3|=0(x-5)²+|y-3|=0所以x=5,y=3代入计算即可
等下再答:
3xy=2x+3y+5(3y-2)(x-1)=7所以3y-2=7x-1=1得y=3x=2xy=6或3y-2=1x-1=7得y=1x=6xy=6所以xy=6
1.y1=y2:-x+2=3x+4=>4x=-2=>x=-1/2y1-1/2y1>y2:-x+2>3x+4=>xx=1y=1带入y=ax+7=>a=-6
x-2=3(2x-3)x-2=6x-96x-x=-2+95x=7x=1.4
原式=-xy²(x²y^4-xy²-1)∵xy²=-2原式=2((-2)²-(-2)-1)=10
∵x-y=4xy∴原式=[2(x-y)+3xy]/[-(x-y)-2xy]=(8xy+3xy)/(-4xy-2xy)=11xy/(-6xy)=-11/6