1) if abc= 1, then (11+a+b−1+11+b+c−1+11+c+a−1)=? A) 0 B) 1 C) 1/ab D) ab Answer: Option BExplanation:Given Exp. =(11+a+b−1+11+b+c−1+11+c+a−1) =11+a+b−1+b−1b−1+1+b−1c−1+aa+ac+1 =11+a+b−1+b−11+b−1+a+aa+b−1+1 =1+a+b−11+a+b−1=1 [∵abc=1]⇒(bc)−1 =a⇒b−1c−1=a and ac=b−1