SOLUTION: I have to find the maximum or minimum value of each quadratic relation y= -2x^2 + 12x y= -3x^2 -21x - 18

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Question 879046: I have to find the maximum or minimum value of each quadratic relation
y= -2x^2 + 12x

y= -3x^2 -21x - 18
Found 3 solutions by Alan3354, josgarithmetic, MathTherapy:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
find the maximum or minimum value of each quadratic relation
y= -2x^2 + 12x
AOS (Axis of Symmetry) is x = -b/2a
x = -12/-4 = 3
------
y = -2*3^2 + 12*3 = 18
Max at (3,18)
=-=-=-=-=-=-=-=-=-=-=-
y= -3x^2 -21x - 18
Same as the 1st one.

Answer by josgarithmetic(39617) About Me  (Show Source):
You can put this solution on YOUR website!
I will do ONE of them and you do the other one based on the method.

Compete the square to put the equation into standard form.
y=-3x%5E2-21x-18
-3%28x%5E2%2B7x%2B6%29, missing term to use is %287%2F2%29%5E2.
-3%28x%5E2%2B7x%2B%287%2F2%29%5E2%2B6-%287%2F2%29%5E2%29
-3%28%28x%2B7%2F2%29%5E2%2B6-49%2F4%29
-3%28%28x%2B7%2F2%29%5E2%2B24%2F4-49%2F4%29
y=-3%28%28x%2B7%2F2%29%5E2-25%2F4%29
highlight%28y=-3%28x%2B7%2F2%29%5E2%2B75%2F4%29
The vertex is a maximum, occurring at highlight%2875%2F4%29, read directly from the standard form equation.


You can learn more about this in the lesson:
http://www.algebra.com/tutors/Completing-the-Square-to-Solve-General-Quadratic-Equation.lesson?content_action=show_dev

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

I have to find the maximum or minimum value of each quadratic relation
y= -2x^2 + 12x

y= -3x^2 -21x - 18


Determine x-coordinate of the vertex, or h, using: h+=+-+b%2F2a

y-coordinate of vertex: k+=+f%28h%29

Then find the y-coordinate of the vertex, which will be a MAXIMUM for both equations. 



You can do the check!! 



If you need a complete and detailed solution, let me know!!



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