Xi1X12解:任取X=Ewnw,(X21X22)由 XW,有 X22=0由 XW,有 Xiz2 = X21 =0( 8)故,X= =( 8)x e P)从而,wnw,86.6子空间的交与和§6.6 子空间的交与和 11 12 1 2 21 22 x x X W W x x = 解:任取 由 X W 1 , 有 22 x = 0 由 X W 2 , 有 12 21 x x = = 0 故, 11 0 0 0 x X = 1 2 ( ) 0 0 0 x 从而, W W x P =