Resposta:
C) # 3sqrt (2) #
Explicació:
arrel quadrada de 18
#color (blanc) ("XXX") = sqrt (18) #
#color (blanc) ("XXX") = sqrt (3xx3xx2) #
#color (blanc) ("XXX") = sqrt (3) xxsqrt (3) xxsqrt (2) #
#color (blanc) ("XXX") = 3xxsqrt (2) #
#color (blanc) ("XXX") = 3sqrt (2) #