Help with math please also if you can put the whole equation please

Apatient is given 50 mg dose of medicine the medicines effectiveness decreases every hour at a constant rate of 40% what is the exponential decay function that models this scenario how much medicine will be left in the patients system after 2 hours

What’s the domain of this function? fastttt

In the polynomial below, what number should replace the question mark to produce a difference of squares? x2 + ? x - 36