Question

Solve the following system of equations: −2x + y = 1 −4x + y = −1

Answer 1

x = 1, y = 3 → (1, 3)

Explanation:

`\left\{\begin{array}{ccc}-2x+y=1\\-4x+y=-1&\text{change the signs}\end{array}\right\\\\\underline{+\left\{\begin{array}{ccc}-2x+y=1\\4x-y=1\end{array}\right}\qquad\text{add both sides of the equations}\\.\qquad2x=2\qquad\text{divide both sides by 2}\\.\qquad x=1\\\\\text{Put it to the first equation:}\\\\-2(1)+y=1\\-2+y=1\qquad\text{add 2 to both sides}\\y=3`