yy+nanoray+20

蓝浅官3040求微分方程yy′+y²/x=1/2的通解
顾泼庾18611415778 ______ yy'+y²/x=1/2【1】齐次方程:yy'+y²/x=0【2】y'+y/x=0,y'=-y/x,dy/y=-dx/x.lh|y|=-ln|x|+lnc,y=c/x【3】【3】是【2】的通解.设【1】的通解:y=u/x【4】,其中u是x的函数.对【4】求导 y'=(xu'-u)/x²【5】【4】【5】代人【1】(u/x)(xu'-u)/x²+(u/x)²/x=1/2,uu'/x²=1/2,2udu=x²dx,u²=(1/3)x³+c,u=±√[(1/3)x³+c]【6】【6】代人【4】,y=±√[(1/3)x³+c]/x【7】【7】是【1】的通解.

蓝浅官3040yy＂+(y')^2+3x^2=0.求通解或通积分. -
顾泼庾18611415778 ______ (yy')'=-3x^2 两边积分:yy'=-x^3+C1 ydy=(-x^3+C1)dx 两边积分:y^2/2=-x^4/4+C1x+C2 y^2=-x^4/2+C1x+C2

蓝浅官30403xxy - 4xyy - 3+5xxy+2xyy+5等于多少 -
顾泼庾18611415778 ______ 3xxy-4xyy-3+5xxy+2xyy+5 =3x²y-4xy²-3+5处丹边柑装纺膘尸博建x²y+2xy²+5 =8x²y-2xy²+2

蓝浅官3040已知x,y为实数,且(x²+y²)(x²+y²+1)=20,求x²+y²的值 -
顾泼庾18611415778 ______[答案] xx+yy看成一个整体 (xx+yy)^2 + (xx+yy) -20=0 因式分解得两根 xx+yy=4或-5 但是xx+yy>=0 所以 xx+yy=4

蓝浅官3040y=f(t)=根号(t - 2),t(x)=x²+2x+3,试用x表示yy=f(t)=根号t - 2,t(x)=x²+2x+3,试用x表示y -
顾泼庾18611415778 ______[答案] Y=f(T)=√(T-2) T(X)=X^2+2X+3 所以Y(X)=F(T)=√(X^2+2X+3-2)=√((X+1)^2) 所以Y(X)=|X+1| 也即 当X>=-1 Y=X+1 当X

蓝浅官3040|x+y - 5|+(xy - 6)(xy - 6)=0,求xx+yy -
顾泼庾18611415778 ______ |x+y-5|+(xy-6)(xy-6)=0=> x+y=5 (1) and xy=6 (2) from (1) x+y =5(x+y)^2 =25 x^2+y^2 = 5-2xy =5-12 =-7

蓝浅官3040已知XX+YY+4X - 6Y+13=0,则X的Y次方是 -
顾泼庾18611415778 ______ XX+YY+4X-6Y+13=0(X+2)²+(Y-3)²=0 X+2=0 Y-3=0 X=-2 Y=3 X的Y次方=-8

蓝浅官3040设集合A={x - y,x+y,xy},b={xx+yy,xx - yy,0},且A=B,求实数x与y的值及集合AB -
顾泼庾18611415778 ______ 因xx-yy=(x-y)(x+y) 所以x-y≠0 x+y≠0 否则xx-yy=0 集合b中就有两个0 于是xy=0 所以x=0或y=0 若y=0, 则x-y=x+y=x A中有两个x,不成立 故y≠0 x=0 这样x-y=xx-yy 即yy=y y=1 或x+y=xx+yy 即y=yy y=1 所以A=B={-1, 1, 0} 希望能帮到你O(∩_∩)O

蓝浅官3040已知x/x - 1=yy+4y - 2/yy+4y - 1,则yy+4y+x的值为 -
顾泼庾18611415778 ______ x/(x-1)=(y²+4y-2)/(y²+4y-1)(x-1+1)/(x-1)=(y²+4y-1-1)/(y²+4y-1) 1+1/(x-1)=1-1/(y²+4y-1) 1/(x-1)=-1/(y²+4y-1) y²+4y-1=1-x y²+4y+x=2

蓝浅官3040若x - y=5乘2的算术平方根,z - y=10,则代数式xx+yy+zz - xy - yz - xz的最小值为
顾泼庾18611415778 ______ xx+yy+zz-xy-yz-xz=x(x-z)+y(y-x)+z(z-y) x-y=5*(根号2) z-y=10 x-z=5*(根号2)-10 =5*(根号2)x-10x-5*(根号2)y+10z =5*(根号2)(x-y)-10(x-z) =50-50*(根号2)+100 =150-50*(根号2)