Answer:
(1,2)
Explanation:
Substitution:
x + 2y = 5 Solve for x
x = -2y + 5 Substitute -2y + 5 in for x in the second equation
4x - 12y = -20
4(-2y + 5) - 12y = -20 Distribute the 4
-8y + 20 - 12 y = -20 Combine the y term
-20y + 20 = -20 Subtract 20 from both sides
-20y = -40 Divide both sides by -20
y = 2
Plug y into either of the 2 original equations to get x.
x + 2y = 5
x + 2(2) = 5
x + 4 = 5
x = 1
The answer is (2,1).
Elimination:
x + 2y = 5 4x - 12y = -20. We want to eliminate with the x or the y. I am going to eliminate the x's that means that I have to multiply the first equation all the way through by -4
(-4)(x + 2y) = (5) (-4) That makes the equivalent expression
-4x - 8y = -20 I will add that to 4x - 12y = -20
4x - 12y = -20
0x -20y = -40
-20y = -40
y = 2. Plug 2 into either the 2 original equation to find x. This time I will select the second original equation to find x.
4x -12y = -20
4x - 12(2) = -20
4x - 24 = -20
4x = 4
x = 1