Which one of the following is a compound surd?
2√48+2√80+2√20
2√12+2√27+2√48=2√(4)(3)+2√(9)(3)+2√(16)(3)=22√3+32√3+42√3=92√3 - simple surds
22√48+32√80+42√20=22√(16)(3)+32√(16)(5)+42√(4)(5)=82√3+122√5+82√5=202√5+82√3 - compound surds
22√72+32√32+42√50=22√(36)(2)+32√(16)(2)+42√(25)(2)=122√2+122√2+202√2=442√3 - simple surds
52√20+42√45+2√80=52√(4)(5)+42√(9)(5)+2√(16)(5)=102√5+122√5+42√5=262√5 - simple surds