(1)5X+2Y=16,Y=1;(2)Y=3/4X,X-8Y=-15;(3)3分之2X+5Y=6分之X-2Y=2;(4)2X+3Y-Z=11,2X+Y-5Z=8,-2X+7Y+Z=19;要过程,
问题描述:
(1)5X+2Y=16,Y=1;(2)Y=3/4X,X-8Y=-15;(3)3分之2X+5Y=6分之X-2Y=2;(4)2X+3Y-Z=11,2X+Y-5Z
=8,-2X+7Y+Z=19;要过程,
答
(1).将Y=1,带入5X+2Y=16,即5X+2=16,5X=14,X=14/5
(2).将Y=3/4X代入X-8Y=-15,即X-3/4X=-15,1/4X=-15,X=-60
(3).2X/3+5Y=2 ①,X/6-2Y=2 ②,
①×2+②×5得,X=84/13,-6/13
(4).2X+3y-z=11 ①,2x+y-5z=8 ②,-2x+7y+z=19 ③,
①+③得,10y=30,即y=3,
①-②得,4z=-3,即z=-3/4,x=5/8
答
(1).将Y=1,带入5X+2Y=16,即5X+2=16,5X=14,X=14/5 (2).将Y=3/4X代入X-8Y=-15,即X-3/4X=-15,1/4X=-15,X=-60 (3).2X/3+5Y=2 ①,X/6-2Y=2 ②, ①×2+②×5得,X=84/13,-6/13 (4).2X+3y-z=11...