Question

помогите пожалуйста оч надо

Answer 1

Решить систему уравнений.

$begin{cases}dfrac{2x+7y}{4}+dfrac{3x-2y}{3} = dfrac{2}{3},\\dfrac{3x+2y}{2}-dfrac{4x-6y}{7} = dfrac{39}{14};end{cases}Longleftrightarrowbegin{cases}dfrac{3(2x+7y) + 4(3x-2y)}{12} = dfrac{2cdot4}{12},\\dfrac{7(3x+2y) - 2(4x-6y)}{14} = dfrac{39}{14};end{cases}Longleftrightarrow\\begin{cases}6x+21y + 12x-8y = 8,\21x+14y - 8x+12y = 39;end{cases}Longleftrightarrowbegin{cases}18x+13y = 8,\13x+26y = 39; |:13end{cases}Longleftrightarrow$

$begin{cases}18x+13y = 8,\x+2y = 3;end{cases}Longleftrightarrowbegin{cases}18x+13y = 8,\x = 3 - 2y;end{cases}\\18(3 - 2y) + 13y = 8,\54 - 36y + 13y = 8,\54 - 8 = 23y,\46 = 23y,\y = dfrac{46}{23},\y = 2;\x = 3 - 2y = 3 - 2cdot2 = 3 - 4 = -1.$

Ответ: $textbf{(x; y) = (-1; 2)}.$