Question

Each system of equations by SUBSTI
x + 3y = 9
4x – 2y = -6

Answer 1

`\huge\boxed{x=0,\ y=3\to(0;\ 3)}`

Explanation:

`\left\{\begin{array}{ccc}x+3y=9&\text{subtract }3y\ \text{from both sides}\\4x-2y=-6\end{array}\right\\\\\left\{\begin{array}{ccc}x=9-3y&(1)\\4x-2y=-6&(2)\end{array}\right`

Substitute (1) to (2):

`4(9-3y)-2y=-6\qquad|\text{use the distributive property}\\\\(4)(9)+(4)(-3y)-2y=-6\\\\36-12y-2y=-6\qquad|\text{subtract 36 from both sides}\\\\-14y=-42\qquad|\text{divide both sides by (-14)}\\\\y=3`

Put it to (1):

`x=9-3(3)\\\\x=9-9\\\\x=0`