求角 ∑=∑(-1)2=∑(x-B-B2x) 2 mn2mn2(Y-B1-B2x)2→ (2 2∑(x-B-B2x)=0() (∑l) 2(x-A-B)X=0(2) 2021/220 Hongfeng Peng Department of 9 Finance, wuhan Univers ity2021/2/20 Hongfeng Peng Department of Finance, Wuhan University 9 求 解 ( ) ( ) ( ) ( ) 2 2 2 1 2 i 2 2 1 2 i 2 1 2 1 2 1 2 2 ˆ ˆ ˆ ˆ ( ) ( ) ˆ ˆ min min ( ) ˆ ˆ ˆ 2 0 (1) ˆ ˆ 2 0 (2) ˆ ˆ ˆ ˆ i i i i i i i i i i i i i u Y Y Y X u Y X Y X Y X X u u           = − − −  − −     = − − − =       = − − − =             =