kymber
How to find the maximum or minimum value of a quadratic function?
Delete
Share
This Question is Closed
2le
Best Response
You've already chosen the best response.
1
You look at the vertex. Are you at the calculus level or the algebra level?
ganeshie8
Best Response
You've already chosen the best response.
2
see the sign of x^2 coeffecient
kymber
Best Response
You've already chosen the best response.
4
Algrebra II, year three in high school. It's the same as the vertex?
ganeshie8
Best Response
You've already chosen the best response.
2
correct, vertex gives us max/min value.
if x^2 coefficient is -ve, its min
if x^2 coefficient is +ve, its max
ganeshie8
Best Response
You've already chosen the best response.
2
its the opposite actually.
if x^2 coefficient is -ve, its max
if x^2 coefficient is +ve, its min
2le
Best Response
You've already chosen the best response.
1
What @ganeshie8 said, that will tell you whether the parabola faces up or down. The point at the vertex will be a min or a max depending on that coefficient.
ganeshie8
Best Response
You've already chosen the best response.
2
|dw:1349465625929:dw|
ganeshie8
Best Response
You've already chosen the best response.
2
so we have minimum value there
kymber
Best Response
You've already chosen the best response.
4
So how do you find the value of it?
ganeshie8
Best Response
You've already chosen the best response.
2
max/min value = f(-b/2a)
ganeshie8
Best Response
You've already chosen the best response.
2
actually it comes from the formula for vertex,
vertex = (-b/2a, f(-b/2a))
phi
Best Response
You've already chosen the best response.
0
for parabola
f(x)= a x^2 + b x +c
the x coordinate of the vertex is -b/(2a)
kymber
Best Response
You've already chosen the best response.
4
Um, like this? |dw:1349465829395:dw|
CliffSedge
Best Response
You've already chosen the best response.
0
Given
\[ax^2+bx+c=a(x-h)^2+k\]
The vertex is located at (h, k).
ganeshie8
Best Response
You've already chosen the best response.
2
|dw:1349465949629:dw|
ganeshie8
Best Response
You've already chosen the best response.
2
that gives the x-coordinate only, y-coordinate gives the max/min value.
ganeshie8
Best Response
You've already chosen the best response.
2
coordinate is just a number i think
kymber
Best Response
You've already chosen the best response.
4
So how do I find the y-coordinate?
ganeshie8
Best Response
You've already chosen the best response.
2
since you got, x-coordinate of vertex = -b/2a = 5
ganeshie8
Best Response
You've already chosen the best response.
2
put that x value = 5, in the quadratic, it gives u y-coordinate of vertex
phi
Best Response
You've already chosen the best response.
0
notice in
x^2 -10x +25
b is -10 (negative 10)
-b/2a is +10/2*1= 10/2 = +5
use 5 for x in the equation to find the y value
kymber
Best Response
You've already chosen the best response.
4
I got it! Thanks guys \(\Large\ddot\smile\)
ganeshie8
Best Response
You've already chosen the best response.
2
glad to hear friend :)
phi
Best Response
You've already chosen the best response.
0
hopefully you got y=0
so the vertex is at (5,0)
and the min value is 0
ganeshie8
Best Response
You've already chosen the best response.
2
and hw do i get that
ganeshie8
Best Response
You've already chosen the best response.
2
smiley..
kymber
Best Response
You've already chosen the best response.
4
Yep, I got 0.
the smiley is \large\ddot\smile
:P
ganeshie8
Best Response
You've already chosen the best response.
2
\( \large\ddot\smile \)
ah latex is beautifyul :)
kymber
Best Response
You've already chosen the best response.
4
Yes it is :D
CliffSedge
Best Response
You've already chosen the best response.
0
Thanks, @kymber for teaching us something.
\[\large \ddot \smile\]
Awesome.
kymber
Best Response
You've already chosen the best response.
4
Hehe \(\huge\ddot\smile\)
hartnn
Best Response
You've already chosen the best response.
0
yeah , kymber also taught me to draw heart ♥
\(\huge \color{red}{♥}\)
CliffSedge
Best Response
You've already chosen the best response.
0
Nice!
kymber
Best Response
You've already chosen the best response.
4
\(\Huge\color{pink}{❥}\) Sideways!
ganeshie8
Best Response
You've already chosen the best response.
2
i thought only AccessDenied is the latex guru... we have so many experts over here hmm :)
ganeshie8
Best Response
You've already chosen the best response.
2
but thats cheating... thats not latex, u using unicode i guess
CliffSedge
Best Response
You've already chosen the best response.
0
You're blowing my mind, @kymber !
kymber
Best Response
You've already chosen the best response.
4
Lol yeah.. it's not a \(\LaTeX\) command. Just alt codes :|
hartnn
Best Response
You've already chosen the best response.
0
still its cool :)
kymber
Best Response
You've already chosen the best response.
4
:D
ganeshie8
Best Response
You've already chosen the best response.
2
:) yea these things i can see also. but sometime back i tried to use crossed swords unicode, and it didnt show up in many browsers :( from then i stopped using unicode, not sure why only few unicode characters show up...
kymber
Best Response
You've already chosen the best response.
4
\(\Huge{⚔}\)
kymber
Best Response
You've already chosen the best response.
4
Lol.
ganeshie8
Best Response
You've already chosen the best response.
2
i see a box, what u see at ur end hmm
kymber
Best Response
You've already chosen the best response.
4
:| I see the swords..
hartnn
Best Response
You've already chosen the best response.
0
i see box also
kymber
Best Response
You've already chosen the best response.
4
What browser are you guys using?
hartnn
Best Response
You've already chosen the best response.
0
chrome O.o
ganeshie8
Best Response
You've already chosen the best response.
2
chrome too
kymber
Best Response
You've already chosen the best response.
4
I'm using Mozilla :P
ganeshie8
Best Response
You've already chosen the best response.
2
firefox ?
hartnn
Best Response
You've already chosen the best response.
0
letme login through mozilla
kymber
Best Response
You've already chosen the best response.
4
Yeah. I switched to Chrome and it's a box. Use Mozilla! :P
ganeshie8
Best Response
You've already chosen the best response.
2
mozilla wins !
hartnn
Best Response
You've already chosen the best response.
0
what kind of black magic is this!
CliffSedge
Best Response
You've already chosen the best response.
0
Firefox is simply superior . .