SOLUTION: The graph of y = 5 + 9x − 2x^2 1. opens downwards and has vertex 2(1/4), 15(1/8) 2. opens upwards and has vertex 2(1/4), −15 (1/8) 3. opens downwards and has vertex −2(1

Question 1142378: The graph of y = 5 + 9x − 2x^2
1. opens downwards and has vertex 2(1/4), 15(1/8)
2. opens upwards and has vertex 2(1/4), −15 (1/8)
3. opens downwards and has vertex −2(1/4), 15 (1/8)
4. opens upwards and has vertex −2(1/4), −15(1/8)
5. opens downwards and has vertex −2(1/4), −15(1/8)
Answer by ikleyn(52898) (Show Source): You can put this solution on YOUR website!
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Since the coefficient at x^2 is negative (its value is -2), the graph opens downwards.


The x- coordinate of the vertex is  x=  (referring to the standard form of the quadratic function y = ax^2 + bx + c,

in which  a= -2, b= 9).


Thus the x- coordinate of the vertex is  x=  =  =   in this case.


Among the given 5 optional answers, only n1 satisfies these conditions -- so, only n1 is the potential candidate.


Now substitute  x=    into the formula of the parabola to verify that y  then equals  .


Do this last check on your own.

I completed my instructions.

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