解下列方程组(1)3x-13y=-16,(2)x+2y+2=0,(3)3t-4s=14,(4)5x+6y=15.2 (5)2m+9n=4.8x+3y=2 7x-4y=-41 5t+4s=2 3x-2y=-0.4 3m-5n=2(6)1/2x+3y=2/3x-3/4y=-29/12
问题描述:
解下列方程组
(1)3x-13y=-16,(2)x+2y+2=0,(3)3t-4s=14,(4)5x+6y=15.2 (5)2m+9n=4.8
x+3y=2 7x-4y=-41 5t+4s=2 3x-2y=-0.4 3m-5n=2
(6)1/2x+3y=2/3
x-3/4y=-29/12
答
(1)3x-13y=-16.(1)
x+3y=2.(2)
(2)×3- (1)得
22y=22
y=1
x=-1
(2)x+2y+2=0,x+2y=-2.(1)
7x-4y=-41.(2)
(1)×2+(2)得
9x=-45
x=-5
y=1.5
(3)3t-4s=14.(1)
5t+4s=2 .(2)
(1)+(2)得
8t=16
t=2
s=-2
(4)5x+6y=15.2.(1)
3x-2y=-0.4.(2)
(1)+(2)×3得
14x=14
x=1
y=1.7
(5)2m+9n=4.8.(1)
3m-5n=-15.(2)
(1)×3-(2)×2得
37n=44.4
n=1.2
m=-3
(6)1/2x+3y=2/3,3x+9y=4.(1)
x-3/4y=-29/12,12x-9y=-29.(2)
(1)+(2)得
15x=25
x=5/3
y=-1/9