Question

Choose the system of equations which matches the following graph.



x – 2y = 8
2x + 4y = 12

x – 2y = 8
2x – 4y = 12

x + 2y = 8
2x + 4y = 12

x + 2y = 8
2x – 4y = 12

Answer 1

lines are parallel.
First step: the answer will be a set of equations where we can see that the "x,y" part (left hand side) of the first is a multiple of the second one.
Second step (maybe): If there are several choices, we have to look at the increase or decrease of the line.

Answer 2

2nd and 3rd set of equations are like that:
[x-2y and 2x-4y] (2nd)
[x+2y and 2x+4y] (3rd)

One of these two lines is decreasing:
x-2y=8 or x+2y=8. when you know that you have found the answer.

Answer 3

or simply check some points

Answer 4

first of these two lines: equation is equivalent to 2y=x-8.-> increasing line.
second of these two lines: equation is equivalent to 2y = -x+8.->decreasing line. This is the correct one.

answer: 3rd.