Question

Допоможіть с 2 варянтом пж дам 55 балов

Answer 1

Ответ:

$1)\ \ \left\{\begin{array}{l}y=5-x\\3x-y=11\end{array}\right\ \ \left\{\begin{array}{l}y=5-x\\3x-(5-x)=11\end{array}\right\ \ \left\{\begin{array}{l}y=5-x\\4x=16\end{array}\right\ \ \left\{\begin{array}{l}y=1\\x=4\end{array}\right\\\\Otvet:\ \ (4;1)\ .$

$2)\left\{\begin{array}{l}x-3y=6\\2y-5x=-4\end{array}\right\ \ \left\{\begin{array}{l}x=3y+6\\2y-5(3y+6)=-4\end{array}\right\ \ \left\{\begin{array}{l}x=3y+6\\2y-15y=-4+30\end{array}\right\\\\\\\left\{\begin{array}{l}x=3y+6\\-13y=26\end{array}\right\ \ \left\{\begin{array}{l}x=0\\y=-2\end{array}\right\ \ \ \ \ \ Otvet:\ \ (0;-2)\ .$

$3)\ \ \dfrac{x}{3}-\dfrac{y}{9}=3\ \ ,\ \ \ 3x-y=27\ \ \ ,\ \ y=3x-27\\\\\\\dfrac{x}{6}+\dfrac{y}{3}=-2\ \ ,\ \ \ x+2y=-12\ \ ,\ \ \ 2y=-x-12\ \ ,\ \ y=-\dfrac{x}{2}-6\\\\\\3x-27=-\dfrac{x}{2}-6\ \ ,\ \ \ 6x-54=-x-12\ \ ,\ \ \ 7x=42\ \ ,\ \ \ \boxed{x=6}\\\\y(6)=3\cdot 6-27=18-27=\boxed {-9}\\\\Otvet:\ \ tochka\ \ (6;-9)\ .$