2^(log4^12)-3^(log9^27)+5^(log25^1/3)
=2^(log2(根号12))-3^(log3(根号27））+5^(log5(根号1/3)
=根号12-根号27+根号(1/3)
=2根号3-3根号3+1/3*根号3
=-2/3*根号3