Which type of questions do we use Arithmetic mean >=Geometric mean euation.

Hi The questions involving maximum and minimum values of terms are the questions where we use Arithmetic mean >= Geometric mean. For example of a question says a+b=12 and a and b are real numbers and find the maximum value of ab so we will use AM>=GM Which means (a+b)/2 >= (ab)^1/2 so we get 6>= (ab)^1/2 squaring both sides we get 36>= ab Hence ab is less than equal to 36 or maximum value of ab will be 36.