分成4块OABO显然逆,等于OB⁻¹A⁻¹O即0 0 0... 0 1/an1/a1 0 0 ...0 00 1/a2 0 ... 0 0...0 0 0... 1/an-1 0
-1的n+1次方 乘以a1a2....an