Решить систему:а) х-у=1    1/х+1/у=5/6б) 4х+ху=6    3х-5ху=39

[latex] \left \{ {{ x=1+y} \atop {1/x+1/y=5/6}} \right. [/latex] [latex] \frac{1}{1+y} + \frac{1}{y} - \frac{5}{6} =0[/latex] [latex]\frac{6y+6+6y-5y-5y^2}{6y(1+y)} =0[/latex] [latex]-5y^2+7y+6=0; y \neq 0;y \neq -1[/latex] [latex]5y^2-7y-6=0; y \neq 0;y \neq -1[/latex] D=49+120=169 y1=2 y2=-3/5 x1=1+y=3 x2=1+y=2/5 [latex] \left \{ {{4x+xy=6} \atop { 3x-5xy=39}} \right. [/latex] [latex] \left \{ {{20x+5xy=30} \atop { 3x-5xy=39}} \right.[/latex] [latex]\left \{ {{20x+5xy=30} \atop { 23x=69}} \right.[/latex] 23x=69 x=3 4x+xy=6;  12+3y=6; 3y=-6; y=-2