用代入法解方程组2x-y=6与5x 2y=-21

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用代入法解方程组2x-y=6与5x 2y=-21
用代入法解方程组4x-3y=10,2x-y=8

2x-y=8得y=2x-8代入4x-3y=10得4x-3(2x-8)=10x=7代入y=2x-8y=6

用代入法解方程组x-y=-6,2x+3y=8.

x-y=-6(1)2x+3y=8(2)由(1)得到:X=Y-6(3)把(3)代入(2)得到:2Y-12+3Y=85Y=20Y=4把Y=4代入(1)得到:X=-2所以X=-2Y=4

用代入法解方程组:2x+3y=-1 4x-y=5

2x+3y=-1(1)4x-y=5(2)由(2):y=4x-5代入到(1):2x+3(4x-5)=-114x=14x=1代入到(2):4-y=5y=-1【秋风燕燕为您答题肯定对】有什么不明白可以对该题

{2x+5y=-2,x=8-3y用代入法解方程组

2(8-3Y)+5Y=-216-6Y+5Y=-216-Y=-2Y=18X=8-3*18=-46

用代入法解方程组:y=3(x-y),x=2(x-y)

y=3(x-y),x=2(x-y)x=0y=0再问:请问,怎样解=0,要过程,谢谢再答:y=3(x-y)=3x-3y4y=3xy=3x/4x=2(x-y)=2x-2y=2x-3x/2=x/2x-x/2

二元一次方程组:用代入法解方程组:y=2x-5;x+3y=-1

将y=2x-5代入x+3y=-1得到x+3(2x-5)=-17x-15=-1x=2代入y=2x-5,y=2*2-5=-1

{3x+2y=8,x-2y=0用代入法解方程组

x-2y=0x=2y3x+2y=83*2y+2y=86y+2y=88y=8y=1x=2y=2*1=2

用代入法解方程组 2x+3y=12 x-2y=-1

2x+3y=-1(1)12x-2y=-1(2)由(1)得12x=-6-18y(3)把(3)代入(2)得20y=-5所以y=-1/4把y=-1/4代入(3)得x=-1/8

用代入法解方程组:2x=3y 3x=2y+1

2x=3y(1)3x=2y+1(2)由(1)得x=3y/2(3)(3)代入(2)得9y/2=2y+1y=2/5代入(3)得x=3/5∴﹛x=3/5,y=2/5是原方程组的解

用代入法解方程组2x-7y=8,3x-8y-10=0,加减法的我会,代入法...

2x-7y=82x=7y+8则:x=7y/2+4把x=7y/2+4代入3x-8y-10=0得:3(7y/2+4)-8y-10=021y/2+12-8y-10=021y/2-8y+2=021y-16y+

用代入法解方程组3x+2y=4x+3y=1

3x+2y=1所以x=(1-2y)/3代入4x+3y=14(1-2y)/3+3y=1解得y=-1.所以x=1

用代入法解此方程组:(x+y)/2+(x-y)/3=6 4(x+y)-5(x-y)=2

(x+y)/2+(x-y)/3=63(x+y)+2(x-Y)=363x+3y+2x-2y=365x+y=36y=36-5x将y=36代入2式4(x+36-5x)-5(x-36+5x)=2144-16x

2x=5(x+y) 3x-10(x+y)=2 用代入法解此方程组

2x=5x+5yy=-3x/5代入3x-10(x-3x/5)=23x-4x=2所以x=-2y=-3x/5=6/5

用代入法解方程组:3x-5y=-9,2x+7y=-6

3x-5y=-9(1)2x+7y=-6(2)有(1)解得:3x=-9+5y即x=(-9+5y)/3(4)代(4)入(2)得2(-9+5y/3)+7y=-6解得y=0代y=0入(4)得x=-3

用代入法解方程组2x+3y=12,3x-4y=17代入法代入法代入法!

2x+3y=12(1)3x-4y=17(2)由(1)得y=(12-2x)/3代入(2)4x-(48-8x)/3=1712x-48+8x=5120x=99所以x=99/20y=(12-2x)/3=7/1

{2x+6y=5,2x+3y=1 用代入法解方程组

解由2x+6y=5得2x=5-6y代入2x+3y=1即5-6y+3y=1即3y=4即y=4/3把y=4/3代入2x+6y=5得2x+8=5即x=-3/2即x=-3/2,y=4/3

{x=2分之1,{3x-y=6用代入法解下列方程组

x=1/2把x带入(2)式子中3*1/2-y=6y=3/2-6y=-9/2

用代入法解方程组5x+3y=36,-x+9y=2

-x+9y=2,x=9y-2代入5x+3y=36:5(9y-2)+3y=3648y=46y=23/24x=9*23/24-2=159/24

用代入法解方程组 {x-y=3 2y+3(x-y)=11}

y=x-3代入方程2y+3x-3y=112(x-3)+3x-3(x-3)=112x-6+3x-3x+9=112x=8x=4y=x-3=1