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Parabola Maths Question Help

The point P(at^2, 2at), t>0 lies on the parabola M with equation y^2=4ax, a>0

a)Show that the equation for the tangent M at P is ty=x+at^2


How do I do this question?
Reply 1
Original post by SpeakNoEvil
The point P(at^2, 2at), t>0 lies on the parabola M with equation y^2=4ax, a>0

a)Show that the equation for the tangent M at P is ty=x+at^2


How do I do this question?


Have you done differentiation so you can fin the equation of a tangent to a curve
Reply 2
Yes but I've messed it up and I don't know how
do you want a solution or an explanation?
Explanation.
You different the y^2=4ax equation to then find out the equation that will give you the gradient of a tangent at any point on the curve.
Reply 4
Original post by SpeakNoEvil
Yes but I've messed it up and I don't know how


differentiate the equation of the parabola (answer in terms of a)

Evaluate gradient function at the point given

use that gradient and the coordinates of the point given

A bit of algebra and hopefully you will get your answer.

If you did all this post your workings in a photo, so someone can check
Reply 5
Original post by AwesomeSauce#1
do you want a solution or an explanation?
Explanation.
You different the y^2=4ax equation to then find out the equation that will give you the gradient of a tangent at any point on the curve.


I'd like a solution so I can cross reference it with my working to see where I've gone wrong
Reply 6
Original post by SpeakNoEvil
I'd like a solution so I can cross reference it with my working to see where I've gone wrong


It is definitely against forum rules for a member to post a full solution.

terribly sorry:smile:
Reply 7
Original post by TeeEm
It is definitely against forum rules for a member to post a full solution.

terribly sorry:smile:


O...kaaay can you just tell me what you get when you differentiate y^2=4ax?
First Step is to differentiate y^2=4ax with respect to x.
next is to plug in the x coordinate of the point P to then find the gradient of the tangent at P. from there you should be able to figure it out :smile:
Reply 9
Original post by SpeakNoEvil
O...kaaay can you just tell me what you get when you differentiate y^2=4ax?


if you use implicit differentiation 2y dy/dx = 4a
so dy/dx = (2a)/y


if you use C1 type differentiation

dy/dy = +/- √a x-1/2
Reply 10
Okay, okay I know what I did now
Reply 11
Original post by SpeakNoEvil
Okay, okay I know what I did now


hope it works :smile:

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