1.用加减消元法解下列方程组:(1){7x-2y=3,9x+2y=-19;(2){6x-5y=3,6x+y=-15;(3){4s+3t=5,2s-t=-5;4){5x-6y=9,7x-4y=-5.
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![1.用加减消元法解下列方程组:(1){7x-2y=3,9x+2y=-19;(2){6x-5y=3,6x+y=-15;(3){4s+3t=5,2s-t=-5;4){5x-6y=9,7x-4y=-5.](/uploads/image/z/1789849-1-9.jpg?t=1.%E7%94%A8%E5%8A%A0%E5%87%8F%E6%B6%88%E5%85%83%E6%B3%95%E8%A7%A3%E4%B8%8B%E5%88%97%E6%96%B9%E7%A8%8B%E7%BB%84%3A%281%29%EF%BD%9B7x-2y%3D3%2C9x%2B2y%3D-19%3B%282%29%EF%BD%9B6x-5y%3D3%2C6x%2By%3D-15%3B%283%29%EF%BD%9B4s%2B3t%3D5%2C2s-t%3D-5%3B4%29%EF%BD%9B5x-6y%3D9%2C7x-4y%3D-5.)
1.用加减消元法解下列方程组:(1){7x-2y=3,9x+2y=-19;(2){6x-5y=3,6x+y=-15;(3){4s+3t=5,2s-t=-5;4){5x-6y=9,7x-4y=-5.
1.用加减消元法解下列方程组:(1){7x-2y=3,9x+2y=-19;(2){6x-5y=3,6x+y=-15;(3){4s+3t=5,2s-t=-5;
4){5x-6y=9,7x-4y=-5.
1.用加减消元法解下列方程组:(1){7x-2y=3,9x+2y=-19;(2){6x-5y=3,6x+y=-15;(3){4s+3t=5,2s-t=-5;4){5x-6y=9,7x-4y=-5.
:(1){7x-2y=3,9x+2y=-19
7x-2y+9x+2y=3-19
16x=-16
x=-1
y=-5
(2){6x-5y=3,6x+y=-15
6x-5y-6x-y=3+15
-6y=18
y=-3
x=-2
(3){4s+3t=5,2s-t=-5;
4s+3t+3(2s-t)=5-3*5
10s=-10
s=-1
t=3
4){5x-6y=9,7x-4y=-5
2(5x-6y)-3(7x-4y)=2*9-3*(-5)
10x-12y-21x+12=18+15
-11x=33
x=-3
y=-4
7x-2y=3,9x+2y=-19
7x-2y+9x+2y=3-19
16x=-16
x=-1
y=-5
(2)6x-5y=3,6x+y=-15
6x-5y-6x-y=3+15
-6y=18
y=-3
x=-2
(3)4s+3t=5,2s-t=-5;
4s+3t+3(2s-t)=5-3*5
10s=-10
s=-1
t=3
4)5x-6y=9,7x-4y=-5
2(5x-6y)-3(7x-4y)=2*9-3*(-5)
10x-12y-21x+12=18+15
-11x=33
x=-3
y=-4