Question

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Answer 1

Ответ: x=-1 ; y=2

$\left \{ {{3x + 2y = 1 \: \: | \times 3 } \atop { - 9x + 7y = 23 \: \: \: \: \: }} \right. \\ \\ \left \{ {{9x + 6y = 3} \atop { - 9x + 7y = 23}} \right. + \\ 13y = 26 \\ y = 2 \\ \\ 3x + 2y = 1 \\ 3x + 2 \times 2 = 1 \\ 3x + 4 = 1 \\ 3x = - 3 \\ x = - 1$

Ответ: x=0,4 ; y=7

$\left \{ {{15x - 3y = - 15 \: \: | \times 7 \: \: \: \: \: \: } \atop {20x - 7y = - 41 \: \: | \times ( - 3)}} \right. \\ \\ \left \{ {{105x - 21y = - 105} \atop { - 60x + 21y = 123}} \right. + \\ 45x = 18 \\ x = 0.4 \\ \\ 15x - 3y = - 15 \\ 15 \times 0.4 - 3y = - 15 \\ 6 - 3y = - 15 \\ - 3y = - 21 \\ y = 7$

Ответ: x=-2 ; y=2

$\left \{ {{7(x + 3) = 3y + 1} \atop {4(2 - x) = 5(y + 1) + 1}} \right. \\ \\ \left \{ {{7x + 21 = 3y + 1} \atop {8 - 4x = 5y + 5 + 1}} \right. \\ \\ \left \{ {{7x - 3y = 1 - 21} \atop { - 4x - 5y = 5 + 1 - 8}} \right. \\ \\ \left \{ {{7x - 3y = - 20 \: \: | \times ( - 5) } \atop { - 4x - 5y = - 2 \: \: | \times 3 \: \: \: \: \: \: \: }} \right.$

$\left \{ {{ - 35x + 15y = 100 } \atop { - 12x - 15y = - 6}} \right. + \\ - 47x = 94 \\ x = - 2 \\ \\ 7x - 3y = - 20 \\ 7 \times ( - 2) - 3y = - 20 \\ - 14 - 3y = - 20 \\ - 3y = - 6 \\ y = 2$

Ответ: x=1 ; y=-2

$\left \{ {{ \frac{x + 3}{4} - \frac{y - 4}{8} = 1 \frac{3}{4} } \atop { \frac{x - 4}{6} + \frac{y + 2}{9} = - \frac{1}{2} }} \right. \\ \\ \left \{ {{ \frac{2x + 6 - y + 4}{8} = \frac{7}{4} } \atop { \frac{3x - 12 + 2y + 4}{18} = - \frac{1}{2} }} \right. \\ \\ \left \{ {{8x + 24 - 4y + 16 = 56} \atop { 6x - 24 + 4y + 8 = - 18}} \right. \\ \\ \left \{ {{8x - 4y = 56 - 16 - 24} \atop { 6x + 4y = - 18 - 8 + 24}} \right.$

$\left \{ {{8x - 4y = 16} \atop {6x + 4y =2 }} \right. + \\ 14x = 14 \\ x = 1 \\ \\ 6x + 4y = 2 \\ 6 \times 1 + 4y = 2 \\ 6 + 4y = 2 \\ 4y = - 4 \\ y = - 2$