求x 3y (x2 y2)的最大值_百度作业帮
来源:学生作业帮助网 编辑:作业帮 时间:2024/08/19 14:25:02
![求x 3y (x2 y2)的最大值_百度作业帮](/uploads/image/f/5733680-32-0.jpg?t=%E6%B1%82x+3y+%28x2+y2%29%E7%9A%84%E6%9C%80%E5%A4%A7%E5%80%BC_%E7%99%BE%E5%BA%A6%E4%BD%9C%E4%B8%9A%E5%B8%AE)
[x(x2y2-xy)-y(x2+x3y)]÷3x2y,=(x3y2-x2y-x2y-x3y2)÷3x2y,=-2x2y÷3x2y,=-23.
x2y2-20xy+x2+81=(xy-10)2+x2-19=0则xy-10=0且x2-19=0得x=+-根号19y=+-10/根号19对于像这种未知数个数多于方程类型的式子,如果能求解,只有一种情况
x3y+2x2y2+xy3=xy(x2+2xy+y2)=xy(x+y)2,∵x+y=5,∴(x+y)2=25,x2+y2+2xy=25,∵x2+y2=13,∴xy=6,∴xy(x+y)2=6×25=1
按字母x的升幂排列就把y看成系数y4-xy3+x2y2+3x3y
∵x+y=4,∴(x+y)2=16,∴x2+y2+2xy=16,而x2+y2=14,∴xy=1,∴x3y-2x2y2+xy3=xy(x2-2xy+y2)=14-2=12.
x,y互为倒数,m,n互为相反数x*y=1m+n=0mxy+n+x2y2=m+n+(xy)²=0+1=1
原式=x4+x3y+4x3y+x2y+4x2y2+4x2y2+xy2+4xy3+xy3+y4,=x3(x+y)+4x2y(x+y)+xy(x+y)+4xy2(x+y)+y3(x+y),=-x3-4x2
(2x4-4x3y-x2y2)-2(x4-2x3y-y3)+x2y2=2x4-4x3y-x2y2-2x4+4x3y+2y3+x2y2=2y3,因为化简的结果中不含x,所以原式的值与x值无关.
x2y2+4xy+4+x2-6x+9=0,(xy+2)2+(x-3)2=0,∵(xy+2)2≥0,(x-3)2≥0,∴xy+2=0,x-3=0,∴xy=-2,x=3.将x=3代入xy=-2中,解得y=
原式=(x^4-2x²y²+y^4)+6xy(x²+2xy+y²)-2xy(x+y)=(x²-y²)²+6xy(x+y)²
方程ax^2+bx+c=0,判断这个方程有没有实数根,有几个实数根,就要用ΔΔ=b^2-4ac若Δ<0,则方程没有实数根Δ=0,则方程有两个相等实数根,也即只有一个实数根Δ>0,则方程有两个不相等的实
解题思路:某项的字母指数和为该项的次数,常数项即为常数解题过程:解:最高项是-3,最高项系数是5和4,常数项是-2
原式=(x3y2-x2y-x2y+x3y2)÷3x2y=(2x3y2-2x2y)÷3x2y=23xy-23.
按x得降幂排列:x^4-4x^3y-x²y²+3xy^3-y^4按y得升幂排列:x^4-4x^3y-x²y²+3xy^3-y^4
∵|x+y+1|≥0,|xy-3|≥0|x+y+1|+|xy-3|=0,∴x+y+1=0,即x+y=-1xy=3xy3+x3y=xy(x²+y²)=yx[(x+y)²-2
应该是X3y-2x2y2+xy3原式=x3y-2x2y2+xy3=xy(x2-2xy+y2)=xy(x-y)2=17/36*6=17麻烦采纳,谢谢!
x+y=4,xy=2后者平方后二式相加再加后者平方
(x-y)2=x2-2xy+y2=9,当x2+y2=13时,13-2xy=9,解得xy=2.当xy=2,x2+y2=13时,x3y-8x2y2+xy3=xy(x2-8xy+y2)=2×(13-8×2)
∵x-y=l,xy=2,∴x3y-2x2y2+xy3=xy(x2-2xy+y2)=xy(x-y)2=2×1=2.
(-三分之二x³y+4x²y²-二分之一xy³)÷(-四分之xy)=-三分之二x³y÷(-四分之xy)+4x²y²÷(-四分之xy