Answer:
[tex]x=-\frac{8}{7}[/tex]
Step-by-step explanation:
We want to find the value of x that satisfies both
- 9x + 4y = 8
and
-3x-y= 4
given the same value of y.
This is the x-value of the point of intersection of the graph of the two lines.
We make y the subject of the bottom equation to get:
y=-3x-4
We substitute y=-3x-4 into the top equation to get:
-9x+4(-3x-4)=8
Expand to get:
-9x-12x-16=8
Group like terms
[tex]-9x-12x=8+16[/tex]
-21x=24
[tex]x=-\frac{24}{21}=-\frac{8}{7}[/tex]
