Question

Given the following system what is the value of x?

Answer 1

y = 2x +1
3x + y = -4

re-write
y = 2x + 1
y = -3x - 4

both equations are equivalent so
2x + 1 = -3x - 4
5x = -5
x = -1

plug in x = -1 into y = 2x +1 to find y

y = 2x +1
y = 2(-1) +1
y = -1

Answer
Solution: x = -1 and y = -1

Answer 2

y = 2x+1
3x +y = -4

replace Y in the 2nd equation with y from the 1st equation:

3x + 2x +1 = -4

3x +2x = 5x, so now you have:

5x +1 = -4

subtract 1 from each side:

5x = -5

divide both sides by 5 to get x

x = -5 / 5

x = -1