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anonymous
 5 years ago
Find the quadratic equation from the following data
The intercepts are (3,0) and (0,18)
anonymous
 5 years ago
Find the quadratic equation from the following data The intercepts are (3,0) and (0,18)

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myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0quadratic has the form f(x)=ax^2+bx+c right?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0we are given that those two points lie on the quatric so we have f(3)=a(3)^2+b(3)c=0 and we have f(0)=c=18 so f(3)=9a3b18=0

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0so we have 9a3b=18 or 3ab=6 if we divide both sides by 3

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0but we have two unknowns so now i'm stuck maybe we should try the form f(x)=a(xh)^2+k

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I don't know much, but if I am correct, the equation must be of the form ay^2+by+c=0

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0As you see there is only one x intercept

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0you can use either form

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0I don't think so, as you see while you use the x form, you are putting the value of x in the equation, and that I think will not work

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0we know the yintercept which is (0,18) so we have f(x)=a(xh)^2+18 now we need to find h and a

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.00=f(3)=a(0h)^2+18=ah^2+18 so we have ah^2=18

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0so either way we still have two unknowns

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0oh i see what you are saying no y=f(x) not x=y

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0its f(x)=ax^2+bx+c or you can use f(x)=a(xh)^2+k

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0we don't know anything else about the parabola?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0If you find any solution please post it here, I will have to leave now, as there is a black out here

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0i was just asking if we know anything else about the parabola?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Iam, I may be able to look at it a bit later. My first impressions of it are to find the slope of the line that joins the two points, use that to perform a rotation back to the xaxis, solve the equation normally and then transform back. Or you could transform the general equation by the same angle and solve straight from the points. Like I said, this is a cursory glance. I don't have time available at the moment to work through it properly, but I will when I can...promise.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0haha, just saw what you wrote, myininaya...

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0And I forgot to say, you may want to translate your points to the right 3 units before rotating...so your points would be (3,0) > (0,0) and (0,18) > (3,18). Hope this is making sense.

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0ignorant, do we know anything else about the parabola?

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0like the vertex or something else?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0No that is all the information I have about it

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0can you make sense out what lokisan is saying? it looks like he has a way to find the equation of the parabola

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Yes, I can get the idea of what he is saying. And I am trying to work it out on pen and paper. If you have any more clue, please post it

myininaya
 5 years ago
Best ResponseYou've already chosen the best response.0do you know derivatives?

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Forget the matrix stuff if you haven't done it. You can use the equations.

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Actually I happen to have learnt that rotation part of matrix

anonymous
 5 years ago
Best ResponseYou've already chosen the best response.0Your problem is: (3,18)=R(x,y) where the ( , ) are vectors and R is the rotation matrix. You need to invert R to find (x,y)=R^{1}(3,18). You'll then have two points, (0,0) and (x,0) (since both points will now be on the xaxis). I'm rushing through this...I've just thought of a 'better' method, but I'm rushed...if I can sort it out later, I will.
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