若x-y=6,xy=-5,求x y的值-搜答案-智慧作业帮

x-5xy+6y=0(√x-2√y)(√x-3√y)=0所以√x=2√y,√x=3√yx=4y或x=9y原式=(8y)/(9y)=8/9或=(14y)/(20y)=7/10

首先化简：原式=7x+4y+xy-5y-6x+6xy=(x-y)+7xy因为,x-y=5,-xy=3所以原式=5-21=-16楼上忘记加负号了~

你好：原式=（7x+4y+xy)-(5y+6x-6xy)……………………把“6”乘进去=7x+4y+xy-5y-6x+6xy=x-y+7xy因为x-y=5,-xy=3所以xy=-3所以,原式=5+7乘

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

(1)+(2)得x²+2xy+y²+5x+5y=0(x+y)²+5(x+y)=0(x+y)(x+y+5)=0∴x+y=0或x+y=-5

0或-5过程看图再问：你QQ好能给我吗？以后不会的可以问你。再答：本人资料里可以找到

1/x+1/y=5两边乘以xy得y+x=5xy∴x+y=5xy3x+4xy+3y/x+3xy+y=[3(x+y)+4xy]/[(x+y)+3xy]=(15xy+4xy)/(5xy+3xy)=19xy/

(x+y)^2=36x^2+y^2+2xy=36x^2+y^2=36-2*2.75=30.5(x-y)^2=x^2+y^2-2xy=30.5-2*2.75=25x-y=5或者-5已知x-y>0x-y=

(x*x+y*y)(x*x+y*y)-4x*x*y*y=(x^4-2x^2y^2+y^4)=(x^2-y^2)^2=0x^2=y^2x/y=±1(x*x+5xy+y*y)/(x*x+2xy+y*y)=

x/y+y/x=(x²+y²)/xy=[(x+y)²-2xy]/xy=(x+y)²/xy-2=25/3-2=19/3

2x+y+6=xy化简得：Y=(2X+6)/(X-1)X不等于0因为正实数x.所以X>0所以X>1函数Y=(2X+6)/(X-1)是单调递增所以X=2为最小值,Y=10所以XY最小值为XY=20

√x(√x+2√y)=√y(6√x+5√y)(√x)²-4√(xy)-5(√y)²=0(√x-5√y)(√x+√y)=0∴√x=5√y√x=-√y舍去原式=[(√x)²-

（7x+4y+xy）-6（5/6y+x-xy）=7x+4y+xy-5y-6x+6xy=x-y+7xy=5+7×(-3)=-16

因为√x(√x+2√y)=√y(6√x+5√y),所以x+2√(xy)=6√(xy)+5y,所以x-4√(xy)-5y=0,所以(√x+√y)(√x-5√y)=0,所以√x+√y=0或√x-5√y=0

把括号打开7X+4Y+XY-5Y-6X+6XY=X-Y+7XY=5+7*(-3)=-16

(7x+4y+xy)-6(六分之五y+x-xy)=7x+4y+xy-5y-6x+6xy=x-y+10xy把x-y=5和-xy=3代入x-y+10xy=5+10*(-3)=5-30=-25所以原式的值是

得y-x=3xyx-y=-3xy原式=-15xy+2xy/-3xy-4xy=-13/-7=13/7

x²＋xy＋5y＝3……………………①y²＋xy＋5x＝﹣3.………………②①＋②得：x²＋2xy＋y²＋5x＋5y＝0﹙x＋y﹚²＋5﹙x＋y﹚＝0

x+y=5xy（2x-3xy+2y)/(x+2xy+y）=[2（x+y）-3xy]/[(x+y)+2xy]=(2×5xy-3xy)/(5xy+2xy)=7xy/7xy=1再问：若x＋1/x＝3,求(x

x^2y+xy^2＝xy×（x+y）＝6×5＝30