例1:用最速下降法求解 m/(x)=1x2+9x2 (9,1) 解 G(x)= x=(00) 9 09 =(9,1)go=Vf(x0)=(9,9) 7.2 080 0 0.8 7.2 0 0 2 9×0.8 g1(-1)2×0例1：用最速下降法求解： ( ) ( ) T f x x x x 9,1 2 9 2 1 min 0 2 2 2 = 1 + = 解： ( ) ( ) ( ) T G x x x x g x 0,0 0 9 1 0 9 * 2 1 =         =         = ( ) ( ) ( ) T T x0 = 9,1 g0 = f x0 = 9,9         − = − = 0.8 7.2 0 0 0 0 0 1 0 g g Gg g g x x T T         − = 7.2 7.2 g1 ( )         −   = − = 2 2 2 1 1 1 1 1 2 1 1 0.8 9 0.8 g g Gg g g x x T T