w=x^2+y^2+z^2+(x+y+z)^2+t(5x+6y+7z-1)&w/&x=2x+2(x+y+z)+5t=0 (1)&w/&y=2y+2(x+y+z)+6t=0 (2)&w/&z=2z+2(x+y+z)+7t=0 (3)5x+6y+7z=1 (4)联立(1)(2)(3)(4) 解得 x=1/58 y=3/58 z=5/58 t=-2/29得到唯一的可能极值点...