Question 1096412: solve system by elimimination
3x-5y=1
9x-y=-17
Answer by addingup(3677)   (Show Source):
You can put this solution on YOUR website! 3x-5y=1 multiply all sides times -3 and add to the other equation:
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
9x-y=-17
+
-9x+15y = -3
-------------
0x+14y = -20
14y = -20
y = -20/14 = -10/7
We now have y, let's find x:
9x−y=−17
9x-(-10/7) = -17
9x+10/7 = -17
9x = -17-10/7
9x = -129/7
x = (-129/7)/9 = (-129*1)/(7*9) = -43/21
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Answer:
y = -10/7
x = -43/21
if you need to check the answers, substitute in the equations for x and y, I'll do one for an example:
3x-5y=1
3(-43/21)-5(-10/7) = 1
-43/7+50/7 = 7/7 = 1 Correct.
|
|
|
