解方程组 1(2x-3y=-1 y=2x-1 ) 2(2x+5y=12 2x+3y=6 )3(3x-2y=6 2x+3y
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解方程组 1(2x-3y=-1 y=2x-1 ) 2(2x+5y=12 2x+3y=6 )3(3x-2y=6 2x+3y=17)4(5x+2y=7 2x+y=1)
1:将y=2x-1代入2x-3y=-1可得:-4x=-4
则x=1
2:用2x+5y=12减去2x+3y=6可得:
y=3
将 y=3代入任何一式可得:
x=-3/2
3:3x-2y=6 ① 2x+3y=17②
①乘以2: 6x-4y=12 ③
②乘以3:6x+9y=51 ④
④-③得:y=3
将y=3代入可得:x=4
4:将2x+y=1的两边同时乘以2可得:4x+2y=2③
用5x+2y=7减去③式可得:x=5
将x=5代入式中得:y=-9
则x=1
2:用2x+5y=12减去2x+3y=6可得:
y=3
将 y=3代入任何一式可得:
x=-3/2
3:3x-2y=6 ① 2x+3y=17②
①乘以2: 6x-4y=12 ③
②乘以3:6x+9y=51 ④
④-③得:y=3
将y=3代入可得:x=4
4:将2x+y=1的两边同时乘以2可得:4x+2y=2③
用5x+2y=7减去③式可得:x=5
将x=5代入式中得:y=-9
解方程组:2(x-y)/3-x+y/4=-1 ,6(x+y)-4(2x-y)=16
2(x+y)-3(x-y)=1 6(x+y)+7(x-y)=51 解方程组
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