Question 42961: I GOT HOMEWORK FROM ALGEBRA BUT I DON'T GET IT AT ALL WE ARE LEARNING ON "SOLVING SYSTEMS BY GRAPHING AND SUBSTITUTION" BUT THAT'S THE PART I DON'T GET CAN YALL PLEASE HELP ME?
HERE'S ONE OF THE PROBLEMS THEY GAVE ME
3x + 2y=-12 & x + 2y=-2
Answer by jmg(22)   (Show Source):
You can put this solution on YOUR website! The answer will be the same but it depends on whether the directions say to solve by substitution or by graphing
BY SUBSTITUTION:
Solve the 2nd equation for x (just because its the easiest)
x + 2y = -2, so x = -2y - 2
Plug this back into the first equation in the system
3x + 2y = -2
3(-2y - 2) + 2y = - 2
-6y - 6 + 2y = - 2
-4y - 6 = -2
- 4y = 4
y = -1
Now plus this back into where you solved for x.
x = -2y - 2
x = -2 * -1 - 2
x = 0
So there is one solution (0, - 1)
If you are working these problems and you get an answer like
x = x or 2= 2, etc. The answer is infinite solutions (all the answers will be the same)
If you get something like 3= 2 or x = y or something weird like that, the answer is no solution. For example, 3 will never equal 2
If you have to solve by graphing, you just graph each line. The point where they meet is the one solution.
If they never meet, it is no solution
If it is the same line, it is infinite solutions
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