SOLUTION: x² - y + 4 = 3x Need to solve for y in terms of x - line by line and tell if a function or not -why or why not Thanks

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Question 87885: x² - y + 4 = 3x
Need to solve for y in terms of x - line by
line and tell if a function or not -why or
why not
Thanks
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!

x² - y + 4 = 3x
Need to solve for y in terms of x - line by
line and tell if a function or not -why or 
why not
Thanks

 x² - y + 4 = 3x

Add -x² to both sides

 x² - y + 4 = 3x
-x²              -x²
--------------------
     -y + 4 = 3x - x²

Add -4 to both sides:

     -y + 4 = 3x - x²
         -4          -4
   ----------------------
     -y     = 3x - x² - 4

Insert a 1 between the nagative sign and the y

        -1y = 3x - x² - 4

Now divide thru by the coefficient of y, which is
-1

      %28-1y%29%2F%28-1%29 = %283x%29%2F%28-1%29 - x%5E2%2F%28-1%29 - 4%2F%28-1%29

          y = -3x + x² + 4

Or in descending powers of x on the right:

          y = x² - 3x + 4

Yes it is a function because:

No matter what value is substituted for x,
only one value of y is obtained, never
two or more for the same x-substitution.

Edwn