Question 1196459: Solve the system by the substitution method.
X+2y=-2
Y=-2x-13
Found 3 solutions by MathLover1, greenestamps, math_tutor2020:
Answer by MathLover1(20850)   (Show Source):
Answer by greenestamps(13200)  (Show Source):
You can put this solution on YOUR website!
The solution from the other tutor is valid (or at least it might be; I didn't bother to check).
But it is not a very smart solution method. Why solve the first equation for x and then substitute in the second equation when the second equation is already solved for y?
Instead, simply substitute y=-2x-13 (from the second equation) in the first equation.
x+2(-2x-13) = -2
x-4x-26 = -2
-3x = 24
x = -8
Then use the given second equation to find y.
y = -2(-8)-13 = 16-13 = 3
ANSWER: (x,y) = (-8,3)
Answer by math_tutor2020(3817)  (Show Source):
You can put this solution on YOUR website!
Another approach:
Graphing out the two equations shows they intersect at (-8,3) which means x = -8 and y = 3 pair up together to form the single solution.
https://www.desmos.com/calculator/o5yrotn6y1
To graph x+2y = -2, we can plug in x = 0 to get...
x+2y = -2
0+2y = -2
2y = -2
y = -2/2
y = -1
So the point (0,-1) is on the graph of x+2y = -2
Repeat for x = 2
x+2y = -2
2+2y = -2
2y = -2-2
2y = -4
y = -4/2
y = -2
The point (2,-2) is on x+2y = -2
The straight line x+2y = -2 goes through (0,-1) and (2,-2)
Follow similar steps to graph out y = -2x-13
Two points on this line are (0,-13) and (1,-15)
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