Rationalize the denominator and simplify:

sqrt a/8 - sqrt a

To rationalize the denominator of this expression, we need to multiply both the numerator and the denominator by the conjugate of the denominator.

The conjugate of sqrt(a)/8 - sqrt(a) is sqrt(a)/8 + sqrt(a).

Therefore, multiplying the expression by sqrt(a)/8 + sqrt(a) gives us:

(sqrt(a)/(8 - sqrt(a)) * (sqrt(a)/(8 + sqrt(a))
= sqrt(a) * sqrt(a) / (64 - a)
= a / (64 - a)

So, the rationalized and simplified expression is a / (64 - a).

Hope this helps.