Given quadratic: x^2 + bx + 72 = 0 has 2 distinct integer roots.

Then, the determinant b^2 – 4ac >0 for standard equation:- ax^2 + bx+ c

Here a = 1, b = b, c = 72

So, b^2 – 4.1.72 >0

= b^2 > 288

Now the least number greater than 288 which is a perfect square is 289. So b >= 17

This ensures the root is real and distinct.