x-y xy=4和3x-y=4的解
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X/2+Y/3=13X/3-Y/4=33X+2Y=13*64X-3Y=3*123X+2Y=784X-3Y=36X=(36+3Y)/4代入1式108+9Y+8Y=31217Y=204Y=12X=18
∵正数x,y满足2x+y-3=0,∴3=2x+y.∴x+2yxy=13(2x+y)(1y+2x)=13(5+2xy+2yx)≥13(5+22xy•2yx)=3,当且仅当x=y=1时取等号.则x+2yx
∵(3x-y-4)2+|4x+y-3|=0,∴3x−y=4①4x+y=3②,①+②得:7x=7,即x=1,将x=1代入①得:3-y=4,即y=-1,则x=1,y=-1.
把X+Y=33乘3得3X+3Y=99用3X+4Y=100去减3X+3Y=99得到Y=1把Y=1带入X+Y=33得X=32X=32Y=1
4X+3Y=6.(1)3X+4Y=15.(2)(1)+(2):7x+7y=21x+y=3(1)_(2):x-y=-9(x+y)/(x-y)=3/-9=-1/3
x^2+y^2=6x-4y-17x^2+y^2-6x+4y+17=0(x-3)^2+(y+2)^2+4=0显然有问题呀!
2x+3y=53y=5-2xy=(5-2x)/33x^2+12xy+y^2=3x^2+12x(5-2x)/3+(5-2x)^2/9x=4时=48-48+1=1
y=3x/5原式=x/(x+3x/5)+(3x/5)/[x-3x/5]-(9x^3/25)/(x^3-9x^3/25)=8/3-3/2-9/16=29/48
(1)XxX+yxy=(x+y)^2-2xy=4^2+2*12=16+28=44(2)XxXxy+Xxyxy=xy*(x+y)=4*(-12)=-48不懂可追问,有帮助请采纳,谢谢!
(1)显然,y=0是原方程的解当y≠0时,∵y'+4y+y^2=0==>dy/dx=-y(y+4)==>dy/(y(y+4))=-dx==>[1/(y+4)-1/y]dy=4dx==>ln│y+4│-
4x+y=5A3x+2y=4BA-B=X-Y=1
3x+4y=2可知x=(2-4y)/3y=(2-3x)/4分别代入x-y5/7x
|3-y|+|x+y|=0,且|3-y|≥0,|x+y|≥0,所以3-y=0,x+y=0,所以y=3,x=-3.所以x+yxy=-3+3-3×3=0-9=0.答:x+yxy的值为0.
分式2x+3yxy中,x、y的值都扩大到原来的2倍,则分式的值缩小为原来的12,故选:B.
应该求(x+y+z)/y(x+y+z)/(y-x)已知x/3=y/5=z/4x/y=5/3z/y=5/4x/z=4/3代进去就好了比如第一个X/Y+1+Z/Y=5/3+1+4/3=4再问:x/y=5/
3X+4Y=23X=2-4YX=(2-4Y)/3X-Y-1/7D
1.x=Ry=R2.x不等于0y不等于03x=Ry=R
5x=y,5:y=x,3x=4y,3:x=4:y,3;x=y:43x+4x=y,中X和Y成比例分别成正比反比正比正比反比正比3x+4x=y确定没抄错?要是抄错了就不成比例了因为Y比X得一个常数才能叫成
(x+y)/2+(x-y)/6=1x/2+x/6+y/2-y/6=12x/3+y/3=12x+y=3(1)3(x+y)-4(x-y)=43x+3y-4x+4y=4-x+7y=4(2)(1)+2*(2)