Question

Determine without graphing whether the given quadratic function has a maximum value, or minimum f(x)=-3x^2+12x-4

Answer 1

the \(-3\) in the front should give you all you need
it tells you that the parabola opens down

Answer 2

http://www.wolframalpha.com/input/?i=-3x^2%2B12x-4
that means it has a maximum, but no minimum

Answer 3

Okay I got the first solution it is max, but what is the value?

Answer 4

the maximum is the second coordinate of the vertex
the first coordinate of the vertex is always \(-\frac{b}{2a}\) which in your case is
\[-\frac{12}{2\times (-3)}=6\] the second coordinate is what you get when you replace \(x\) by \(6\)

Answer 5

okay I understand that part what I don't understand is when you take 3(2)+12(2)-4

Answer 6

or 6 our answer?

Answer 7

no

Answer 8

i have no idea where \(3(2)+12(2)-4\) came from
what you need to compute for the maximum is
\[-3(6^2)+12(6)-4\]

Answer 9

oh okay, so I was doing it wrong, actually I was looking the wrong problem... okay now do you start figuring out the problem, please help....