Answer:
-One Equation: is set equal to a variable
Example:
y = 2x + 1
x + 3y = -12
You already have y, plug it back into x + 3y = -12
x + 3(2x + 1) = -12
x + 6x + 3 = -12
7x + 3 = -12
(Subtract 3 from each side)
7x = -15
(Divide by 7)
x = - 2.14
-No Equation: is set equal to a variable
Example:
2x + y = 10
4× + 2y = -3
Subtract 2x from each side of 2x + y = 10, you should get y= -2x + 10. Now that you have found y, substitute y into 4x+ 2y = -3.
4x + 2(-2x + 10) = -3
4x + -4x + 20 = -3
(Subtract 20 from each side)
4x + -4x = -23
(Add 4x and -4x)
0 = -23
No Solution
-Both Equations: are set equal to a variable
Example:
y = x + 5
y = -x + 3
(you already have y so plug it into the other equation to solve for x)
-x + 3 = x + 5
(Add -x on both sides)
3 = 2x + 5
(subtract 5 from both sides)
-2 = 2x
(Divide by 2 on each side)
x = -1
I hope this helped!