解方程组:1.{3x+2y=14 2.{x-5y=0 3.{x÷2+y÷3=2 {x=y+3 {3x+2y=17 {0.2x+0.3y=2.8

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解方程组:1.{3x+2y=14 2.{x-5y=0 3.{x÷2+y÷3=2 {x=y+3 {3x+2y=17 {0.2x+0.3y=2.8
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解方程组:1.{3x+2y=14 2.{x-5y=0 3.{x÷2+y÷3=2 {x=y+3 {3x+2y=17 {0.2x+0.3y=2.8
解方程组:1.{3x+2y=14 2.{x-5y=0 3.{x÷2+y÷3=2 {x=y+3 {3x+2y=17 {0.2x+0.3y=2.8

解方程组:1.{3x+2y=14 2.{x-5y=0 3.{x÷2+y÷3=2 {x=y+3 {3x+2y=17 {0.2x+0.3y=2.8
3x+2y=14 ①
x-5y=0 ②
① -②×3得:
17y=14
y=14/17
y=14/17代入②得:
x-5·14/17=0
x=70/17
3x+2y=17 ①
0.2x+0.3y=2.8 ②
②×10得:
2x+3y=28 ③
①×2-③×3得:
6x+4y-6x-9y=34-84
y=10
y=10代入①得:
3x+20=17
x=-1

{3x+2y=14 {x=4
{x=y+3 {y=1
2.{x-5y=0 {x=5
{3x+2y=17 {y=1
3.{x÷2+y÷3=2 {x=-4
{0.2x+0.3y=2.8 {y=12