Rewrite a fractional exponent as a radical when evaluating a definite integral?

Basically, I can't figure out how on earth my Calc teacher got his answer. The problem is:

integrate (2-t)âˆšt dt on the interval [0.2]

1. 2t^(1/2) - t^(3/2)

2. 4/3t^(3/2) - 2/5t^(5/2) on the interval [0,2]

3. plugging in, I get 4/3*2^(3/2) - 2/5*2^(5/2) - 0

4. This is where I get lost. Somehow he got (8âˆš2)/3 - (8âˆš2)/5, which simplifies to (16âˆš2)/15. I understand the fist half before the minus sign, but I don't understand the 2/5*2^(5/2) to (8âˆš2)/5 at all...