Trình bày ứng dụng của vi phân toàn phần trong việc tính xấp xỉ giá trị của một hàm số hai biến. Cho ví dụ.

Which account has the highest effective annual interest rate? not necessary but show how you got your answer. a. account 1: interest is compounded quarterly at an annual rate of 4.20%.b. account 2: interest is compounded monthly at an annual rate of 4.15%.c. account 3: interest is compounded semiannually at an annual rate of 4.10%d. account 4: interest is compounded annually at a rate of 4.25%.