Question:
Solve the following linear system of equations:
y = 4x + 23
y = 2x + 9
Solution:
Lets denote the above equation by:
y = 4x + 23 EQUATION 1
y = 2x + 9 EQUATION 2
If we substitute equation 2 ( the y ) in equation 1 we obtain:
2x +9 = 4x +23
solve for x:
2x-4x = 23-9
this is equivalent to:
-2x = 14
thus:
x = -7.
Now, to obtain y, replace x = -7 in equation 2:
y = 2(-7)+9 = -14+9 = -5
then we can conclude that the solution of this system of linear equations is:
x = -7
y = -5