for any real x the expression 2(k-x)[x+(x²+k²)^0.5] cannot exceed a)1 b)2 c)4 d)none of these

apply AM≥GM to the expression (k-x) and (x+(x²+k²)) and find the minimum value of AM and equate it as the maximum value of the GM.on simplification,you'll get the answer as 2