SOLUTION: Solve the following system of equations: y = 3x + 15 2x − 3y = −17 What is the y-coordinate of the solution?

Algebra ->  Coordinate Systems and Linear Equations -> SOLUTION: Solve the following system of equations: y = 3x + 15 2x − 3y = −17 What is the y-coordinate of the solution?      Log On


   

Question 1098994: Solve the following system of equations:
y = 3x + 15
2x − 3y = −17

What is the y-coordinate of the solution?
Found 2 solutions by Fombitz, ikleyn:
Answer by Fombitz(32388) About Me  (Show Source):
You can put this solution on YOUR website!
y-15=3x
x=%28y-15%29%2F3
and
2x=3y-17
x=%283y-17%29%2F2
So then setting them equal to each other,
%28y-15%29%2F3=%283y-17%29%2F2
2%28y-15%29=3%283y-17%29
2y-30=9y-51
-7y=-21
Solve for y.

Answer by ikleyn(52788) About Me  (Show Source):
You can put this solution on YOUR website!
.
From the first equation, you just have an expression for y.


Substitute it into the second equation. You will get


2x - 3*(3x+15) = -17  ====>  2x - 9x - 45 = -17  ====>  -7x = -17 + 45  ====>  -7x = 28  ====>  x = 28%2F%28-7%29 = -4.


Then from the first equation  y = 3*(-4) + 15 = -12 + 15 = 3.


Answer.  y-coordinate of the solution is y = 3.