How to figure out a equation given the variables

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The discussion focuses on deriving a formula for final velocity (vf) using the variables time (t), initial position (xi), final position (xf), and acceleration (a). The initial attempt using the equation vf = vi + at was deemed incorrect. A revised approach involved manipulating the kinematic equations, leading to the realization that the correct relationship is (xf - xi) - (1/2at^2) = vi*t. By substituting vi back into the equation and rearranging, the final expression for vf was derived as ((xf - xi) - (1/2at^2)/t) + at = vf. This highlights the importance of correctly applying kinematic equations to solve for unknown variables.
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Homework Statement


Starting from the constant-acceleration kinematic equations, write a formula that gives vf in terms of t, xi, xf, and a.

Homework Equations


The Attempt at a Solution


I tried using vf = vi + at but it was incorrect. Is there another way where i can solve for vf using the 4 needed variable above? thanks
Also I have tried using this : (xf-xi)+(1/2at) = vi then substitute vi with this equation vf = vi+at. After that I got (xf-xi)+at = vf but it was still incorrect.
 
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(xf-xi)+(1/2at) = vi
This equation is wrong.
It should be
(xf-xi)-(1/2at^2) = vi*t
From the equation vf = vi + at find vi and put it in the above equation and rearrange to get vf
 
what I got was ((xf-xi)-(1/2at^2)/t))+at = vf
 
Kennyh said:
what I got was ((xf-xi)-(1/2at^2)/t))+at = vf

vi*t = (vf - at)t = vf*t -a*t^2
 

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