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
1个回答

(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