You can
put this solution on YOUR website!The reciprocal means "1 divided by ..." So the reciprocal of the square root of 3 means:
.

.
But convention is that you do not leave a radical (in this case

) in the denominator.
The way you get rid of the square root of 3 is to multiply this fraction by

which is equivalent to multiplying the fraction by 1 because the denominator of the multiplier
is equal to the numerator.
.
This multiplication is:
.

.
But in the denominator the multiplication of

is equal to

. As a
result the form the answer takes is:
.

.
And this is the conventional form of the reciprocal of the square root of 3.
.
Hope this helps you to explain the problem to your son.