Question 717542
{{{512^(-1/3)}}}
If you have trouble with negative and/or fractional exponents, I have found that it can be helpful to factor the exponent in a special way:<ol><li>If the exponent is negative, factor out -1.</li><li>If the exponent is a fraction and its numerator is not 1, then factor out the numerator.</li></ol>Using this on your expression...
1. The exponent is negative so we factor out -1:
{{{512^((-1)*(1/3))}}}
2. The exponent is a fraction. But its numerator is a 1 so we do nothing.<br>
Once the exponent is factored this way, each factor tells you an operation to perform:<ul><li>A factor of -1 in the exponent means we should find a reciprocal.</li><li>A factor that is a fraction (with a numerator of 1) means find a root of the kind specified by the denominator.</li><li>If there is another factor it will be a positive whole number which means what it usually means.</li></ul>And these operations can be done in any order! So choose an order that looks easier.<br>
So for:
{{{512^((-1)*(1/3))}}}
we will find a reciprocal and find a cube root. Which should we start with? If we start with the reciprocal we get a fraction (since the reciprocal of 512 is 1/512). Then we would be finding a cube root of a fraction. Or we could start with the cube root and then find the reciprocal. This second path looks easier to me.<br>
After a little effort we should be able to figure out that {{{8^3 = 512}}} so the cube root of 512 is 8. And the reciprocal of 8 is 1/8. So:
{{{512^(-1/3) = 512^((-1)*(1/3)) = 1/8}}}
Since 512 was a perfect cube we never really needed radical notation. But we could use it anyway:
{{{512^(-1/3) = 512^((-1)*(1/3)) = 1/root(3, 512) = 1/8}}}