Question

Y=3x+13 2x=y-9 Solve for x and y points using addition method

Answer 1

$y=3x+13 \\ 2x=y-9 \ \ \ |-y-2x \\ \\ y=3x+13 \\ \underline{-y=-2x-9} \ \ \ \hbox{add the sides} \\ y-y=3x-2x+13-9 \\ 0=x+4 \\ x=-4 \\ \\ y=3x+13=3 \times (-4)+13=-12+13=1 \\ \\ \boxed{(x,y)=(-4,1)}$

Answer 2

Y = 3x + 13
y = -2x + 9
2y = x + 22
2y = x + 22
 2        2
y = 1/2x + 11
1/2x + 11 = 3x + 13
-1/2x       -1/2x       
           11 = 2 1/2x + 13
         -13                 - 13
            -2 = 2 1/2x
             -2 = 2 1/2x
         2 1/2    2 1/2
          -0.8 = x
y = 3(-0.8) + 13
y = -0.24 + 13
y = 12.76
(x, y) = (-0.8, 12.76)