柯西不等式,(X^2+Y^2+Z^2)*(1+4+9)>=(x+2y+3Z)^2=14,等式成立条件X/1=Y/2=Z/3 所以x=√14/14 y=2√14/14 z=3√14/14
(x+2y+3z)^2=14
14(x^2+y^2+z^2)=(x+2y+3z)^2,化简得(2x-y)^2+(3x-z)^2+(2z-3y)^2=0
所以y=2x,z=3x,代入得x+y+z=3*14*(1/2)/7
6/(根号14) x,y,z分别是1/(根号14) 2/(根号14) 3/(根号14)
柯西不等式......(x²+y²+z²)(x1²+y2²+z2²)≥(xx1+yy1+zz1)² 相等条件....x/x1=y/y2=z/z2