The product of 40 and a number m, is a 2-digit number that greater than 40. The value of m is

With a,b>0 satisfy a+b=2.Find the minimum of A=\(\left(1-\dfrac{4}{a^2}\right)\left(1-\dfrac{4}{b^2}\right)\)

P/s:The exam of the excellent teacher of Duc Tho district