SOLUTION: Looking at {{{f(x)=-0.2x^2+12x+11}}} Does the graph of this equation open up or down? How did you determine this?

Algebra ->  Polynomials-and-rational-expressions -> SOLUTION: Looking at {{{f(x)=-0.2x^2+12x+11}}} Does the graph of this equation open up or down? How did you determine this?       Log On


   

Question 130290: Looking at f%28x%29=-0.2x%5E2%2B12x%2B11

Does the graph of this equation open up or down? How did you determine this?
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Using the general equation y=ax%5E2%2Bbx%2Bc we can use this to determine the direction in which the parabola opens up.

Remember if a%3E0 (ie "a" is a positive number), then the parabola opens up like this

graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+x%5E2%29+


On the other hand, if a%3C0 (ie "a" is a negative number), then the parabola opens down like this

graph%28+500%2C+500%2C+-10%2C+10%2C+-10%2C+10%2C+-x%5E2%29+



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Answer:

So in our case a=-0.2 which is less than zero. So the parabola opens down.