Mohon Bantuan nya ^_^

nomor 3....
   3√2 + 9√8
= 3√2 + 9√(4.2)
= 3√2 + 9.2√2
= 3√2 + 18√2
= 21√2

nomor 4....
   7√5 x 2√20
= 7.2 √(5.20)
= 14 √400
= 14.20
= 140

3.) 3√2+18√2=21√2
4.) 7√5 X 4√5= 140