Ответ(ы) на вопрос:
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1.
[latex]\left\{{{3x+7y-3=0}\atop{7x+9y-7=0}}\right.[/latex]
[latex]\left\{{{3x+7y=3}\atop{7x+9y=7}}\right.[/latex]
[latex]\left\{{{3x+7y=3/-7}\atop{7x+9y=7/3}}\right.[/latex]
[latex]\left\{{{-21x-49y=-21}\atop{21x+27y=21}}\right.[/latex]
[latex]-21x-49y+21x+27y=-21+21[/latex]
[latex]-49y+27y=0[/latex]
[latex]-22y=0[/latex]
[latex]y=0[/latex];
[latex]3x+7y-3=0[/latex]
[latex]3x+7*0-3=0[/latex]
[latex]3x+0-3=0[/latex]
[latex]3x-3=0[/latex]
[latex]3x=3[/latex]
[latex]x=1[/latex]
Ответ: x = 1; y = 0.
2.
[latex]\left\{{{6x-13y+1=0}\atop{5x+10y-20=0}}\right.[/latex]
[latex]\left\{{{6x-13y=-1}\atop{5x+10y=20}}\right.[/latex]
[latex]\left\{{{6x-13y=-1/-5}\atop{5x+10y=20/6}}\right.[/latex]
[latex]\left\{{{-30x+65y=5}\atop{30x+60y=120}}\right.[/latex]
[latex]-30x+65y+30x+60y=5+120[/latex]
[latex]65y+60y=125[/latex]
[latex]125y=125[/latex]
[latex]y=1[/latex];
[latex]5x+10y-20=0[/latex]
[latex]5x+10*1-20=0[/latex]
[latex]5x+10-20=0[/latex]
[latex]5x-10=0[/latex]
[latex]5x=10[/latex]
[latex]x=2[/latex]
Ответ: x = 0; y = 1.
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