How do you solve the system of equations #y=-9x-21# and #y=5x+7#?
Look at the equations:
Because both equations equal (y), they both equal the same.
If an equations says "
Therefore when i take the equation:
Now isolate (x):
Alternatively, you could solve it with graphs. Get a coordinatsystem and look at where the graphs intersect. They will intersect where graph 1 is equal to graph 2, which is essentially the same as what we just did :)