SOLUTION: The graph of y = –2x2 + 15x + c contains (3, 89). Find the value of c.

Algebra ->  Quadratic Equations and Parabolas  -> Quadratic Equations Lessons  -> Quadratic Equation Lesson -> SOLUTION: The graph of y = –2x2 + 15x + c contains (3, 89). Find the value of c.      Log On


   

Question 689954: The graph of y = –2x2 + 15x + c contains (3, 89). Find the value of c.
Answer by Stitch(470) About Me  (Show Source):
You can put this solution on YOUR website!
Given: Y+=+-2X%5E2+%2B+15X+%2B+C
And the point (3,89)
------------------------
That means that when you plug 3 into the equation for X, then Y will be 89.
Rewrite the equation
89+=+-2%2A%283%29%5E2+%2B+15%2A%283%29+%2B+C
Simplify the equation
89+=+-2%2A9+%2B+45+%2B+C
Simplify the equation
89+=+-18+%2B+45+%2B+C
Combine like terms
89+=+27+%2B+C
Subtract 27 from both sides
highlight%2862+=+C%29