a) 4/√2+9/√3+15/5√3-4√25/5√2=
4√2/2+9√3/3+3√3/3-4√2/2=
2√2+3√3+√3-2√2=6√3
b)15/√5+6/√12-8/√20-15/√75=
15√5/5+6√3/2-8√5/2-15√3/5=
3√5+3√3-4√5-3√3=-√5
c)16/√8+(√36-√16)/√2-14/√98=
16√2/4+(6-4)√2/2-14√2/7=
4√2+√2-2√2=3√2
d)24/√24-25/√150-36/216+15/√54=
24√6/12-25√6/30-36√6/36+15√6/18=
2√6-5√6/6-√6+5√6/6=√6
