x,y∈R+求证:(x+y)(x^2+y^2)(x^3+y^3)>=8x^3y^3
1个回答
x>0,y>0
则x+y>=2√xy>0
x²+y²>=2xy>0
x³+y³>=2√(x³y³)>0
都是正数
相乘
(x+y)(x²+y²)(x³+y³)>=8x³y³
相关问题
已知x,y是正数,求证:(x+y)(x^2+y^2)(x^3+y^3)>=8x^3y^3
x,y是正数,求证:(x+y)(x^2+y^2)(x^3+y^3)大于等于8x^3y^3.
已知X,Y都是正数,求证:(x+y)(x^2+y^2)(x^3+y^3)≥8x^3y^3
求证x^8+y^8+z^8>=x^3y^2z^2+x^2y^3z^2+x^2y^2z^3
3x-2y=9 x-3y=2 x+y=5 x+2y=3 y=x 2x+y=8
已知x,y,z∈R,且x+y+z=8,x2+y2+z2=24求证:[4/3]≤x≤3,[4/3]≤y≤3,[4/3≤z≤
2x+3y/4+2x-3y/3=7和2x+3y/3+2x-3y/2=8 x=?,y=?
①1/2(8x-6y)+3(y-x/3) ②3(2x-3y)-2(3x-2y) ③2(x²-3xy)-3(y&
计算:(1)(-7x2-8y2)•(-x2+3y2)=______;(2)(3x-2y)(y-3x)-(2x-y)(3x
1.X-3=Y+4 x=3Y 2.x-2y=3 3x-8y=13