4xy对x积分

弘虏轮2045怎么对4ydx+(4x+1)dy 积分 -
訾舒泄13783926806 ______ 4ydx+(4x+1)dy=(4ydx+4xdy)+1dy=4d(xy)+1dy 积分以后就是4xy+y. 注意d(xy)=ydx+xdy

弘虏轮2045x²y²+x²+y²+1=4xy,求x,y的值 -
訾舒泄13783926806 ______ x²﹢y²﹢x²y²﹢1=4xy x²﹢y²﹢x²y²﹢1-4xy=0(x²﹢y²-2xy)+(x²y²-2xy﹢1)=0(x-y)²+﹙xy-1﹚²=0 ∵(x-y)²≧0,﹙xy-1﹚²≧0 ∴(x-y)²=0, ﹙xy-1﹚²=0 ∴x-y=0,xy=1 所以x=y=1或x=y=-1

弘虏轮2045若x+y=3,xy= - 4,则3x - (4xy - 3y)值为 -
訾舒泄13783926806 ______ 原式=3x-4xy+3y =3(x+y)-4xy =3x3-4x(-4) =25

弘虏轮2045已知x^2 - y^2=4xy,求(x^4+y^4)/(xy)^2的值 -
訾舒泄13783926806 ______ (x^4+y^4)/(xy)^2=(x^4+y^4-2x^2y^2+2(xy)^2)/(xy)^2=((x^2-y^2)^2/(xy)^2+2=(4xy)^2/(xy)^2+2=16+2=18

弘虏轮2045如果非零实数x,y满足4x方+y方=4xy,求y除以x的值.
訾舒泄13783926806 ______ 4x²+y²=4xy 得4x²-4xy+y²=(2x-y)²=0 所以2x=y, x除以y的值是1/2

弘虏轮2045已知1÷x - 1÷y=3则÷的值为多少 -
訾舒泄13783926806 ______ 解:已知1÷x-1÷y=3得x分之1-y分之1=3xy分之y-xy分之x=3xy分之(y-x)=3y-x=3xyx-y=-3xy则(5x+xy-5y)÷(x-xy-y)=[5*(x-y)+xy]÷[(x-y)-xy]=[5*(-3xy)+xy]÷(-3xy-xy)=...

弘虏轮2045设二维随机变量xy的概率密度f(x,y)=4xy求P(2X+Y -
訾舒泄13783926806 ______[答案] 首先画出,积分区域D 得到P(2X+Y

弘虏轮2045已知(x - 3)²+|y+2|=0,求代数的值:(2x²y - 4xy²) - ( - 3xy²+x²y) -
訾舒泄13783926806 ______ (x-3)²+|y+2|=0 (x-3)²=0,|y+2|=0 x=3,y=-2 (2x²y-4xy²)-(-3xy²+x²y) =2x²y-4xy²+3xy²-x²y=2x²y-x²y-4xy²+3xy²=x²y-xy²=xy(x-y)=-2*3*[3-(-2)]=-6*5=-30

弘虏轮2045已知x方+4y方=4xy,求x+2y/x的值 -
訾舒泄13783926806 ______[答案] x方+4y方=4xy x²-4xy+4y²=0 (x-2y)²=0 x=2y x+2y/x=(2y+2y)/(2y)=2

弘虏轮2045(x - y+x - y分之4xy)乘(x+y - x+y分之4xy)=? -
訾舒泄13783926806 ______[答案] =[(x-y)²+4xy]/(x-y)*[(x+y)²-4]/(x+y) =(x+y)²/(x-y)*(x-y)²/(x+y) =(x+y)(x-y) =x²-y²