x y-x=73 求XY
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![x y-x=73 求XY](/uploads/image/f/888588-36-8.jpg?t=x+y-x%3D73+%E6%B1%82XY)
x-xy=8(1)xy-y=-9(2)则有(1)-(2):X-XY-XY+Y=X+Y-2XY=8-(-9)=17
令F(XY)=1/XY+XY,当XY=1的时候,F(XY)=2,最小.(可由函数图形象得出).XY趋于正无穷大的时候F(XY)趋于正无穷大,XY无限趋于零的时候F(XY)趋于正无穷大.所以XY越接近1
-xy(x^2y^5-xy^3-y)=-(xy^2)^3+(xy^2)^2+xy^2=-(-2)^3+4-2=8+4-2=10
xy-12=4x+y≥2√(4xy)=4√(xy)xy-4√(xy)-12≥0(√(xy)-6)(√(xy)+2)≥0√(xy)≤-2,√(xy)≥6因为√(xy)≥0所以√(xy)≥6xy≥36所以
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×(
3xy-[2xy-2(xy-2分之3xy)+xy]+3xy=6xy-[2xy-2xy+3xy+xy)=6xy-4xy=2xy=2×3×3分之1=2
x=-1,y=-6或x=6,y=1代入式子得x^2-xy^2=37或30x^2y+xy^2=-42或42
(x-xy)+(xy-y)=40-20x-xy+xy-y=20x-y=20(x-xy)-(xy-y)=40-(-20)x-xy-xy+y=60x+y-2xy=60
y'+xy=0的通解y.=Ce^(-x).特解y=x^2-2x.通解y=Ce^(-x)+x^2-2x.再问:不好意思啊,之前一直在忙别的。没有及时回复,首先谢谢你的回答。但是我觉得你的回答有点问题。‘
xy为正实数,则有2x+y>=2根号(2xy)即:xy-6>=2根号(2xy)设根号(xy)=t>0,则xy=t^2t^2-6>=2根号2tt^2-2根号2t-6>=0(t-3根号2)(t+根号2)>
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
x²+xy=99x(x+y)=9*11x(x+y)=9*(9+2)x=9,y=2
x/[sec(xy)-y]dx/dy.
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
已知xy+x+y=6则xy+x+y+1=(x+1)(y+1)=7=7×1因为x,y都是自然数(非负整数)所以x+1,y+1≥1所以只能x+1=7y+1=1即x=6,y=0或x+1=1,y+1=7即x=
3(x^2-xy)-xy+y^2=3(x^2-xy)-(xy-y^2)=3*5-(-3)=15+3=18
原式=-xy²(x²y^4-xy²-1)∵xy²=-2原式=2((-2)²-(-2)-1)=10
答:xy=x-e^(xy)e^(xy)=x-xy=x(1-y)两边对x求导:(xy)'e^(xy)=1-y-xy'(y+xy')e^(xy)=1-y-xy'ye^(xy)+xy'e^(xy)+xy'=