Q.

If a = 2² × 3ˣ, b = 2² × 3 × 5, c = 2² × 3 × 7 and LCM (a, b, c) = 3780, then x is equal to:

1 1  
2 2  
3 3  
4 0  

Ans.

(3)

If LCM (a,b,c) = 3780
By prime factorisation of 3780

3780=22×33×5×7      LCM (a,b,c)=22×33×5×7                 (i)a=22×3x;b=22×3×5; c=22×3×7LCM (a,b,c)=22×3x×5×7                 (ii)Comparing (i) and (ii), we get  𝑥 = 3