Question

Алгебра 7 клас срочно допоможіть

Answer 1

1)

$\displaystyle\bf\\\left \{ {{4x + 5y = 11 \: \: | \times ( - 6) } \atop {6x + 8y = 15 \: \: | \times 4}} \right. \\ \displaystyle\bf\\ + \left \{ {{ - 24x - 30y = - 66} \atop { 24x + 32y = 60 }} \right. \\ \\ 32y - 30y = 60 - 66 \\ 2y = - 6 \\ y = - 6 \div 2 \\ y = - 3 \\ \\ 4x + 5 \times ( - 3) = 11 \\ 4x - 15 = 11 \\ 4x = 11 + 15 \\ 4x = 26 \\ x = 26 \div 4 \\ x = 6.5$

Ответ: ( 6,5 ; - 3 )

2)

$\displaystyle\bf\\\left \{ {{3x + y = 4} \atop {5x - 2y = 14 }} \right. \\ \displaystyle\bf\\\left \{ {{y = 4 - 3x} \atop {5x - 2(4 - 3x) = 14 }} \right. \\ \\ 5x - 8 + 6x = 14 \\ 11x = 14 + 8 \\ 11x = 22 \\ x = 22 \div 11 \\ x = 2 \\ \\ y = 4 - 3 \times 2 \\ y = 4 - 6 \\ y = - 2$

Ответ: ( 2 ; - 2 )