Question

7 класс система уравнений

Answer 1

$1)\; \; \left\{\begin{array}{l}3x-5y=4\\ax+15y=-12\end{array}\right\quad \dfrac{3}{a}=\dfrac{-5}{15}=\dfrac{4}{-12}\; \; ,\\\\\\\dfrac{3}{a}=-\dfrac{1}{3}=-\dfrac{1}{3}\; \; \; \Rightarrow \; \; \; \; \boxed {\; a=-9\; }$

$2)\; \; \left\{\begin{array}{ccc}-2x+3y=-1\\4x+ay=2\end{array}\right\quad \Rightarrow \quad \dfrac{-2}{4}=\dfrac{3}{a}=\dfrac{-1}{2}\\\\\\-\dfrac{1}{2}=\dfrac{3}{a}=-\dfrac{1}{2}\; \; \; \Rightarrow \; \; \; \; \boxed {\; a=-6\; }$