... = 21 2 .Tac´oA = 12 21 2 33 −1 − 21 2 2 21 3µh1× 2 → h1h 2 × 2 → h 2 −→−→ 24 21 66 2 21 4 21 3µh 2 − 3h1→ h 2 h3− ... x1= x 2 = −1, x3=0,x4=1) 32. x1+2x 2 +3x3− 2x4=6,2x1− x 2 − 2x3− 3x4=8,3x1+2x 2 − x3+2x4=4,2x1− 3x 2 +2x3+ x4= −8.(DS. x1=1,x 2 =2, x3= ... x 2 +2x3− 3x4=5,3x1+3x3− 10x4=8.(DS. Hˆe.vˆo nghiˆe.m)15.x1+2x 2 +3x3− 2x4=1,2x1− x 2 − 2x3− 3x4 =2, 3x1+2x 2 − x3+2x4= −5,2x1− 3x 2 +2x3+...