# Homework Help: Root of equation

1. Mar 13, 2012

### xzibition8612

1. The problem statement, all variables and given/known data

2t^3-4t-5=0
Find t

2. Relevant equations

[-b-sqrt(b^2-4ac)]/2a

3. The attempt at a solution

The answer is sqrt(2/3). No idea how this came about. I tried plugging in the equation and got it wrong. :( Please help I've been struggling over this for 5 hours.

2. Mar 13, 2012

### Mentallic

$$x=\frac{-b\pm \sqrt{b^2-4ac}}{2a}$$
$$y=ax^2+bx+c$$
But now that I look at it, are you sure you wrote the cubic down correctly? The real root definitely isn't $\sqrt{2/3}$.