186k views
2 votes
Solve by substition: y=3x+14 y=-4x

User Rhan
by
8.1k points

2 Answers

3 votes
-4x = 3x + 14
-4x - 3x = 14
-7x = 14
-7x/-7 = 14/-7
x = -2
User Gtrig
by
7.7k points
6 votes
Hey there!
This is a pretty convienient problem because we already have the value of y!
We can simply plug it in the other equation to find x and then plug it back in for y.
We have:

-4x = 3x + 14
Subtract 3x:

-7x = 14
To isolate x, divide both sides by -7

x = -2

Now, plug it back in to the y = -4x to find the value of y.

y = -4(-2)
y = 8

Now, let's check our answer.

8 = 3(-2) + 14
8 = -6 + 14
8 = 8

Therefore, our answer is (-2, 8).

Hope this helps!
User Dougnukem
by
8.7k points