how to solve this

Question

2y-4x=8

y=2x-7

solve for one variable

substitue that in the other equation

substitue that value in one of the original equations

Answer 1

So, your 2nd equation is already solved for y. Since y = 2x - 7, we can substitute 2x - 7 for y in the 1st equation. Remember that 2y means 2 times y.

2(2x - 7) - 4x = 8

4x - 14 - 4x = 8

-14 = 8

0 = 22

Well, huh, that's not true! That means that there is no solution and your lines are parallel.

Answer 2

According to the first equation, dividing by 2 gives y = 2x + 4.

However, the second has y = 2x - 7. This is never = 2x + 4, just as -7 is never = +4.

So the 2 equations are inconsistent, and no solution exists to satisfy both simultaneously.

Answer 3

The second equation already says y = 2x - 7, that means "y" and "2x - 7" are the same thing. So in the first equation (2y - 4x = 8), wherever you see a "y", you can replace it with a "2x - 7". So:

2(2x - 7) - 4x = 8 [now distribute the 2 to get rid of the parenthesis to get:

4x - 14 - 4x = 8 [combine the 4x and -4x to get:

-14 = 8 Then ask yourself, does -14 equal 8? The answer, of course, is "no". That means there is no solution to this set of equations. In other words, these two lines are parallel lines that never intersect.