and B={x≥0:√x(√x−4)−3|√x−2|+6=0} ‌‌‌x−4√x−3√x+6+6=0‌ when ‌√x−2≥ ‌‌‌⇒‌‌x−7√x+12=0 ‌‌‌⇒‌‌x−4√x−3√x+12=0 ‌‌‌⇒‌‌√x√x−4)−3(√x−4)=0 ‌‌‌√x=4,√x=3 ‌‌‌⇒‌‌x=16,9 When √x−2<0 ‌‌‌⇒‌‌x−4√x+3√x−6+6=0 ‌‌‌⇒‌‌x−√x=0 ‌‌‌⇒‌‌√x(√x−1)=0 &‌‌‌⇒‌‌√x=0,1 ‌‌‌⇒‌‌x=0,1 ‌‌‌⇒‌‌n(B)=4 ‌ Now as ‌A‌ and ‌B‌ are mutually exclusive sets ‌ N(A∪B)=4+4=8