7「2 -6 A=LU= 21 3-7 -341 4 (2)解Ux=y (1)解Ly=b 1 7y1「10 21 y2 19 1-341y」-30」 得y=10,y2=19-20=-1,y=34-30=4 解得：x3=1,x2=2,x=3 即y=10,-1,4) 所以方程组的解为x=(3,2,1)。 This documentis prduced byria version ofPrnhVisit www.prinashcfor more informionThis document is produced by trial version of Print2Flash. Visit www.print2flash.com for more information