1) В

[tex]\displaystyle\bf\\\left \{ {{5x - 3y = 4} \atop { - x + y = 2 \: \: | \times 3}} \right. \\ \displaystyle\bf\\ + \left \{ {{5x - 3y = 4} \atop { - 3x + 3y = 6 }} \right. \\ \\ 5x - 3x = 6 + 4 \\ 2x = 10 \\ x = 10 \div 2 \\ x = 5 \\ \\ - 5 + y = 2 \\ = 2 + 5 \\ y = 7[/tex]

Ответ: ( 5 ; 7 )

2) Д

[tex] \displaystyle\bf\\\left \{ {{ - 2x + y = 8 \: \: | \times 3} \atop {6x - 3y = - 24 }} \right. \\ \displaystyle\bf\\ + \left \{ {{ - 6x + 3y = 24} \atop {6x - 3y = - 24 }} \right. \\ \\ 6x - 6x + 3y - 3y = 24 - 24 \\ 0 = 0[/tex]

3) Г

[tex]\displaystyle\bf\\\left \{ {{4x - 2y = 1} \atop { - 2x + y = 3 \: \: | \times 2 }} \right. \\ \displaystyle\bf\\ + \left \{ {{4x - 2y = 1} \atop { - 4x + 2y = 6 }} \right. \\ \\ 4x - 4x + 2y - 2y = 1 + 6 \\ 0\neq7[/tex]

4) Б

[tex]\displaystyle\bf\\\left \{ {{(y - 4)(y + 1) = 0} \atop {x = - 2 }} \right. \\ \\ (y - 4)( y+ 1) = 0 \\ y_{1} =4 \\ y_{2} = - 1[/tex]

Ответ: ( - 2 ; 4 ) и ( - 2 ; - 1 )