Question

Solve the system of equations given below. -5x = y – 5 -2y = -x-21

Answer 1

Answer:

x = -1, y = 10 → (-1, 10)

Step-by-step explanation:

$\left\{\begin{array}{ccc}-5x=y-5&\text{subtract y from both sides}\\-2y=-x-21&\text{add x to both sides}\end{array}\right\\\left\{\begin{array}{ccc}-5x-y=-5&\text{multiply both sides by (-2)}\\x-2y=-21\end{array}\right\\\underline{+\left\{\begin{array}{ccc}10x+2y=10\\x-2y=-21\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad11x=-11\qquad\text{divide both sides by 11}\\.\qquad x=-1\\\\\text{put the value of x to the first equation:}\\\\10(-1)+2y=10\\-10+2y=10\qquad\text{add 10 to both sides}\\2y=20\qquad\text{divide both sides by 2}\\y=10$