Question

Solve the system of linear equations by substitution.
5x + 2y = 9
-0.5x - y = 7.5

Answer 1

Explanation:

`\displaystyle\\\left \{ {{5x+2y=9\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ } \atop \cdot2} \right. \\\\\\\left \{ {{5x+2y=9} \atop {-x-2y=15}} \right. \\+\\--------\\4x=24\ \ \Rightarrow\ x=24:4\Rightarrow\ x=6\\\\y=-0.5x-7.5=-0.5\cdot6-7.5=-3-7.5=-10.5\\\\\boxed{(x;y)=(6;-10.5)}`