4.what is the orgin and why is it important?

The origin is the centre of the axis, and has the coordinates (0,0). It is important because it is essentially the "origin" of the number on the axis. 

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.