i) Let x be any nonnegative number. By considering an appropriate function, explain briefly that sqrt(x) is a real number.

ii) Let a and b be nonnegative numbers. Use i) to explain why (sqrt(a)-sqrt(b))^2 is greater than or equal to 0

iii) Hence deduce that if a and b are nonnegative numbers,then a+b >or= 2(sqrt(ab))

let a and b be nonnegative numbers. Prove that a+b=2(sqrt(ab)) is and only if a=b