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**Last_Singularity** Observe that $\displaystyle x = 81^{1/4} = (81^{1/2})^{1/2} = 9^{1/2} = 3$

So to find $\displaystyle x$, square root 81 twice, once to get 9 and a second time to get the answer: 3.

Raising a number to the one-fourth power does not mean that you are square rooting it four times. Instead, it is asking: which number multiplied by itself four times gets you the original number? In other words, which number multiplied by itself four times gets you 81? That number is defined as $\displaystyle 81^{1/4}$, or 3.