anonymous
  • anonymous
how to determine a & b valuesin the equation: y=ax^2 +bx-4 if the vertex is located at (-2,-1) Please help!
Mathematics
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get our expert's

answer on brainly

SEE EXPERT ANSWER

Get your free account and access expert answers to this
and thousands of other questions.

anonymous
  • anonymous
how to determine a & b valuesin the equation: y=ax^2 +bx-4 if the vertex is located at (-2,-1) Please help!
Mathematics
jamiebookeater
  • jamiebookeater
I got my questions answered at brainly.com in under 10 minutes. Go to brainly.com now for free help!
At vero eos et accusamus et iusto odio dignissimos ducimus qui blanditiis praesentium voluptatum deleniti atque corrupti quos dolores et quas molestias excepturi sint occaecati cupiditate non provident, similique sunt in culpa qui officia deserunt mollitia animi, id est laborum et dolorum fuga. Et harum quidem rerum facilis est et expedita distinctio. Nam libero tempore, cum soluta nobis est eligendi optio cumque nihil impedit quo minus id quod maxime placeat facere possimus, omnis voluptas assumenda est, omnis dolor repellendus. Itaque earum rerum hic tenetur a sapiente delectus, ut aut reiciendis voluptatibus maiores alias consequatur aut perferendis doloribus asperiores repellat.

Get this expert

answer on brainly

SEE EXPERT ANSWER

Get your free account and access expert answers to this
and thousands of other questions

myininaya
  • myininaya
did you enter in -2 for x and -1 for y
Hero
  • Hero
4a = b
Hero
  • Hero
-1 = a(-2)^2 +(4a)(-2) - 4

Looking for something else?

Not the answer you are looking for? Search for more explanations.

More answers

Hero
  • Hero
a = -3/4?
Hero
  • Hero
b = 3?
Hero
  • Hero
How did you get b = 2?
myininaya
  • myininaya
so a has different value too
Hero
  • Hero
myininaya, how come you just can't do things the normal way?
anonymous
  • anonymous
so you cant just sub -2 into one equation and -1 into another, andthe other number equal zero? or does that not mke any sense?
anonymous
  • anonymous
I'm just a little confused by the math you did above..lol
Hero
  • Hero
myininaya likes to go overboard with her methods
myininaya
  • myininaya
ok hero but there are two possible outcomes
Hero
  • Hero
Not if you do it the way I did. I used direct substitution
myininaya
  • myininaya
We have a parabola concave up and also concave down at vertex
myininaya
  • myininaya
Here I will do it the way I told you to
anonymous
  • anonymous
Im familar with substitution , just not the way shown above im only in gr 10 so mabye thats why i dont get yours?
Hero
  • Hero
a = -3/4 b = -3
anonymous
  • anonymous
^did you make 2 equations and then substitutions?
Hero
  • Hero
something like that
anonymous
  • anonymous
-1 = a(-2)^2 +(4a)(-2) - 4 :this is what you did, why did you sub 4a into the equation? is there a more strait forward way to do this? :)
Hero
  • Hero
myininaya, if you use the direct substitution method, you wouldn't have to worry about getting hung up like that. The parabola opens upward or downward depending on the value of a. Since I calculated a to be negative, I'm pretty sure it opens downward and there is only one possibility
Hero
  • Hero
I replace b with 4a because b = 4a
Hero
  • Hero
I also replaced x = -2 and y = -1
Hero
  • Hero
Which are all of the known values
Hero
  • Hero
according to x = -b/2a, there's only one possible a
anonymous
  • anonymous
alright im still a bit confused but thanks for your help!! :)
myininaya
  • myininaya
\[-1=a(-2)^2+b(-2)-4\] \[-1=4a-2b-4 => 3=4a-2b\] We also know the vertex which is (-2,-1) \[y=a(x-h)^2+k\] we also know h=-2 and k=-1 so we have \[y=a(x+2)^2-1=a(x^2+4x+4)-1=ax^2+4ax+4a-1=ax^2+4ax+(4a-1)\] \[=>4a=b , -4=4a-1\] \[=>3=b-2b=> 3=-b=> b=-3\] if b=-3 then a=-3/4 hmmm how do we get the other possibility ok so maybe there is only one lol
Hero
  • Hero
:D
Hero
  • Hero
There's only one possibility because there's only one a value that would work in order to get both sides equal for x = -b/2a
Hero
  • Hero
if a was squared, then there would be two possibilities
myininaya
  • myininaya
I didn't think about the y-intercept
myininaya
  • myininaya
The parabola has vertex (-2,-1) and -4 is lower so this graph will be concave down
myininaya
  • myininaya
|dw:1327278866372:dw|
Hero
  • Hero
yup
myininaya
  • myininaya
we can't not have it concave up is has to come to that -4
myininaya
  • myininaya
so my bad hero you win this one
Hero
  • Hero
I don't win many so I will savor this :P
myininaya
  • myininaya
hey lady do you understand what i did up there?
anonymous
  • anonymous
A bit lol but thanks!
Hero
  • Hero
mya likes to confuse people then ask if they understand
myininaya
  • myininaya
you also have to use the vertex form like i did to find another equation or two
anonymous
  • anonymous
im still pretty confused but i can move on to a different qestion on my assignment lol thanks for the help on this one tho :)
Hero
  • Hero
You're still here?

Looking for something else?

Not the answer you are looking for? Search for more explanations.