I am readind about Heisenberg's Uncertainty Principle and although the main formula most texts use is
$$\Delta x\Delta p_{x}\geq \frac{\hbar}{2}$$
or equivalently
$$\Delta x\Delta p_{x}\geq \frac{h}{4\pi}$$
I have seen it written as
$$\Delta x\Delta p_{x}\geq \hbar$$
or
$$\Delta x\Delta p_{x}\geq h$$
First of all, are all those correct formulas? If so, then how are they equivalent with each other?
