25^(3/2) - 1/4 = √25^3 - 1/4
= √(25^2 25) - 1/4
= 25√25 - 1/4
= 255 - 1/4
= 125 - 1/4
= 124.75

Therefore, 25^(3/2) - 1/4 is equal to 124.75.