Need help with some basic math/exponential rules I don't understand. How do I get from a to be here?

Question

See image. I've looked up just about every rule I can find and I can't figure out how I am supposed to arrive at that answer. Can someone explain to me what has been done step by step here?

Answer 1

$$\frac12=0.5$$ $$0.5-1=-0.5$$ $$x^{-0.5}=\frac 1{x^{0.5}}$$ $\frac 12\cdot \frac 1{x^{0.5}}$ is the result you want.

Answer 2

$$0.5=\frac12$$ $$0.5-1=-0.5$$ $$x^{-n}=\frac1{x^n}$$

That should be enough to figure it out

Answer 3

This is the big one here

$x^{-a} = \frac {1}{x^a}$

As for the rest of it,

$0.5 = \frac 12$

$x^{1-0.5} = x^{-\frac 12}$

$0.5x^{0.5-1} = \frac 12 x^{-\frac 12} = \frac {1}{2x^\frac 12}$

The other big one we haven't talked about.

$x^\frac 1a = \sqrt [a]{x}$

$0.5x^{0.5-1} = \frac {1}{2\sqrt x}$