# How do you solve by substitution #y = 3x – 4# and #9x – 3y = 14#?

##### 1 Answer

These equations represent parallel lines so there is no solution.

#### Explanation:

We can attempt a solution as follows:

[1]

[2]

Using [1], substitute

[3]

Simplify

[4]

Obviously **impossible**!

So, what went wrong?

If we take [1] and rearrange it into standard form:

[5]

then multiplying by 3

[6]

What are we to make of the combination of [2] and [6]?

If we graph these two equations, we would see that they form a pair of parallel lines. (Go ahead; try it. I'll wait).

If two lines are parallel then they do not intersect and there is no point where they are equal.