Example
Use substitution to solve this system of equations.
y + 3x = -4
y=x+4
The second equation tells you
that y = x +4, so you can substitute
x + 4 for y in the first equation and
solve for x.
y + 3x = -4
(x + 4) + 3x = -4
4x + 4 = -4
4x = -8
x = -2
problems 1-7.
ution
Now you can find the value of y.
You can substitute -2 for x into
either equation and solve for y.
Try using the second equation.
y=x+4
y=-2 +4
y = 2
The solution is (-2,2).
Explain why you substitute x + 4 for y in the first
equation of the system in the example.