Solve for t: Rearrange Equation σ=ωi*t+½α*t^2

[oj600]

Homework Statement

I need to find t in the following:
σ = ωi*t + ½ α*t2 (this is ment to be t squared)

Homework Equations

The Attempt at a Solution

I got:
t + t(squared) = 2 * σ/(ωi * α)

is this then simply
t = sqrt(2 * σ/(ωi * α)) ??

 

[justsof]

σ = ωi*t + ½ α*t^2
You can't write this as:
t + t^2 = 2 * σ/(ωi * α)
You can't divide only 1 half of the equation by something... then you'll just change it.
Like dividing by 1/2 a would give:
t^2 + 2ωi/a*t = 2σ/a
You just can't simplify it like you do.
And your third step is not correct either.

This is a Quadratic Equation ( http://en.wikipedia.org/wiki/Quadratic_equation ), look up how to solve these (you could make use of the quadratic formula).

 

[ammontgo]

Quadratic Formula:
[PLAIN]http://dl.dropbox.com/u/4645835/MATH/Quadratic.gif