32x=56y那么xy=-搜答案-智慧作业帮

实数x,y,z,满足那么x+y=6,z^2=xy-9,∴xy=z^+9,(x-y)^=(x+y)^-4xy=-4z^>=0,∴z=0,(x+y)^z=6^0=1.

5x²-3xy-4y²-11xy-7x²＋2y²=5x²-7x²＋2y²-4y²-3xy-11xy=-2x²-

xy=6/(x+y)xy(x+y)=6,已知x和y是整数,则xy和(x+y)也是整数,而6=2*3=1*6当xy=3时,x+y=2,无整数解当xy=1时,x+y=6,无整数解当xy=6时,x+y=1,

设函数f（x,y)=sin(x+y),那么f(0,xy）=(sinxy)应该是sin0+sinsy=0+sinxy=sinxy再问：limsinxy\2x=()补充x→0，y→3另外一道题

xy/(x+y)=2∴xy=2(x+y)(3xy-x-y)/(3x-5xy+3y)=[6(x+y)-x-y]/[3x+3y-10(x+y)]=5(x+y)/[-7(x+y)]=-5/7

x-y=6（1）,xy=7,（2）由（1）得y=6+x（3）把（3）带入（2）的x（6+x）=7解得x=1或者x=-7x=1时y=7或者x=-7时y=1x^2-y^2=-48或者48

3xy+4x+2y=3xy+2(2x+y)=3*7+2*8=21+16=37

xy+(x+y)=8,那么xy=8-(x+y)由基本不等式得：xy≤[(x+y)/2]²所以8-(x+y)≤[(x+y)/2)]²即：(x+y)²+4(x+y)-32≥0

(1/x)-(1/y)=(y-x)/xy=-xy/xy=-1

答：x^2+3xy-2y^2=0两边同时乘以1/(xy)得：x/y+3-2y/x=0设x/y=t,则y/x=1/t上式方程即为：t+3-2/t=0t^2+3t-2=0解得t=(-3±√17)/2所以x

(3x-2y+3xy)-(x-4y-2xy)=3x-2y+3xy-x+4y+2xy=2x+2y+7xy=2(x+y)+5xy=2×3-5×2=-4

x+y=6（x+y）平方=6平方x平方+2xy+y平方=36x平方-2xy+y平方=36-4xy(x-y)平方=36-4x3(x-y)平方=24x-y=±2根号6如还有新的问题,请不要追问的形式发送,

2(x+xy)-[(xy-3y)-x]-(-xy)=2x+2xy-xy+3y+x+xy=3x+3y+2xy=3（x+y）+2xy=3*（-2）+2*3=0

1/x-1/y=2(y-x)/xy=2y-x=2xy(3x+5xy-3y)/(x-xy-y)=[5xy-3(y-x)]/[-xy-(y-x)]=(5xy-6xy)/(-xy-2xy)=-xy/-3xy

y=5-x(5-x)x=-3解得2组解x1=(5+根号37)/2y1=(5-根号37)/2x2=(5-根号37)/2y2=(5+根号37)/2

2x+3y-3xy+4xy-3x-4y+7=(2x-3x+3y-4y)+4xy-3xy+7=(-x-y)+xy+7=-(x+y)+xy+7=-4-1+7=2

0.5x²+xy+0.5y²=0.5(x²+2xy+y²)=0.5(x+y)²=0.5

3x-3y=xy3/x-3/y=1(两边同除xy)1/x-1/y=1/3

解；2*(3*4)=2*[2×3×4-(3+4)]=2*17=2×2×17-(2+17)=68-19=49

x²-4xy+4y²=0(x-2y)²=0则x=2y,因为xy≠0,则x≠0且y≠=0那么(x-y)/(x+y)=(2y-y)/(2y+y)=y/(3y)=1/3