SOLUTION: I need help with this problem: f(x)=-4x^2+ 4x-1 This is what the problem asks: a)use the quad formula to find zeros b)Find Max or min value c)sketch the graph This is wha

Question 108951: I need help with this problem:
f(x)=-4x^2+ 4x-1
This is what the problem asks:
a)use the quad formula to find zeros
b)Find Max or min value
c)sketch the graph
This is what I have done so far:
-4+/- sqr rt(4^2-4(-4)(-1))/2(-4)
Note: This should be set up using the quad formula
This is what I came up with:
x= -4+/- sqrt(16-16)/ -8
Note: also set up in quad formula.
My problen is what to to with the 16s. If I subtract them that leaves Zero. I'm stuck here. I can look at the equation and tell it will be a max value but what are the zeros? Please help?

Answer by bucky(2189) (Show Source): You can put this solution on YOUR website!
You are correct so far. The sqrt(16 - 16) is zero. If you replace it with zero in your equation
for x you get:
.

.
And you are further correct that this graph rises to a peak and then drops back down.
.
This means that you only have one zero and it occurs when x is equal to . So the graph
just touches the x-axis at its peak and that "touching" is at the value x = .
.
And at this point the maximum value is y = 0. The graph looks like this:
.

.
You did everything correctly, but just didn't recognize how to interpret your answer.
.
Hope this helps you to see how to view answers when the terms in the radical reduce to zero.
.

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