Negative Fractional Exponent problem

[jdoyle]

Hi All,

Can anyone walk me through this problem. This is from an old med school entry test.

The answer is 81 but I can't work out how the x terms cancel.



3x(3x^ -1/3)^3

Thanks in advance

John

 

[meldraft]

$$\frac{3x}{(^3\sqrt{x})^3}3^3=\frac{3x}{x}3^3=27*3=81$$

Given of course that x is not 0.

 

[jdoyle]

Hi Meldraft,

It looks so simple I don't know why I didn't do it that way. Thanks very much.

John

 

[meldraft]

It's very easy to put that 3^3 in the denominator by accident