根号144分之49×根号9分之144
=√(49/144)×√(144/9)
=7/12×12/3
=7/3
根号3又16分之1+根号4
=√(49/16)+√4
=7/4+2
=15/4
根号16－根号81
=√16-√81
=4-9
=-5