how to plot the fractions on a number line -1/6 and 4/3

The question says: "Put each fractional expression into standard form by rationalizing the denominator."   It gives the fraction (9)/(4th root)(2).  I multiplied both the numerator and the denominator by (4throot)(2). The answer key says "((9)(4th root)(8))/(2)", but I'm not sure how to get to that answer. Should I be multiplying the fraction by the starting denminator, or should I change the exponents?

How do you rewrite this into one fraction: (1/a+b)+(2/a)-(3/b)

How did you go from x^5 to x^10 on the denominator? You divided everything by x^5 and then just the bottom by x^10