Problem description:

I want to know in detail, that is to say, how this formula is derived, why it is derived like this, and what is the significance of this?

Analysis:

Matching repayment method, also known as matching principal and interest repayment method, refers to monthly matching repayment of loan principal and interest.

The characteristic of equal repayment method is that the monthly repayment amount remains unchanged during the whole repayment period (except when the interest rate is adjusted). The advantage is that the borrower can accurately grasp the monthly repayment amount and arrange the family's income and expenditure in a planned way.

Matching principal and interest repayment method:

Monthly repayment amount: a * [I * (1+I) n]/[(1+I) n-1]

Note: a loan principal I loan monthly interest rate n loan month

Average capital repayment method:

Monthly principal repayment: None

Monthly interest payable: 30 days

Note: A loan principal I loan monthly interest rate n loan month A loan residual principal in the nth month, a 1=a, a2=a-a/n, a3=2-2*a/n ... and so on, the actual number of days in the nth month of dn, February is 28, March and April is 3/kloc-0.