Question 1127390
<br>
One general method for evaluating expressions like this is to consider an expression of the form<br>
{{{(sqrt(a)+sqrt(b))^2}}}<br>
Expanded, this expression is equal to<br>
{{{(a+b)+2sqrt(ab)}}}<br>
Then solving for the square root of that expression means finding two numbers a and b whose sum is the real part of the expression and whose product is the radicand of the inner square root.<br>
Using that process directly, with the fractions, will be a bit awkward; to simplify the process, put the expression in the radical in a form with a common denominator that is a perfect square.  That will allow us to take out the fractions using a common denominator, leaving us integers to work with.<br>
{{{sqrt(7/12)-sqrt(3)/3 = sqrt(21/36)-12*sqrt(3)/36}}}<br>
Then<br>
{{{sqrt(sqrt(21/36)-12*sqrt(3)/36) = (sqrt((21)-12*sqrt(3)))/6}}}<br>
Now we need to simplify<br>
{{{(sqrt((21)-12*sqrt(3)))}}}<br>
using the process described at the beginning of my response.<br>
We need to rewrite the expression under the radical in the exact required form, with a coefficient of 2 on the inside radical:<br>
{{{(sqrt((21)-2*sqrt(108)))}}}  [divide outside the radical by 6; multiply inside by sqrt(36)]<br>
Now, using the form shown earlier, we look for two numbers with a sum of 21 and a product of 108; the numbers are 9 and 12.  So<br>
{{{(sqrt((21)-2*sqrt(108))) = sqrt(12)-sqrt(9)}}}<br>
Then to finish the problem we divide by 6:<br>
{{{sqrt(12)/6-sqrt(9)/6 = 2*sqrt(3)/6-3/6 = sqrt(3)/3-1/2}}}<br>
The directions say to express the solution in the form x + sqrt(y).  So we have to express sqrt(3)/3 as sqrt(y):<br>
{{{sqrt(3)/3 = sqrt(3)/sqrt(9) = sqrt(3/9) = sqrt(1/3)}}}<br>
So...<br>
ANSWER: {{{sqrt(sqrt(7/12)-sqrt(3)/3) = (-1/2)+sqrt(1/3)}}}