Final answer:
The formula obtained by solving M=pr(1+r)^n/((1+r)^n-1) for P is known as the Principal formula, which reflects the initial loan amount.
Step-by-step explanation:
When solving the formula M=pr(1+r)^n/((1+r)^n-1) for P, you are essentially isolating the principal amount which represents the initial loan amount. The formula would be rearranged to solve for P, which is the present value (principal) of the series of payments. After rearranging the formula, the name of the formula that represents the isolated P is the Principal formula.
To provide a clear example, consider the original formula where M represents the monthly payment, p is the principal, r is the monthly interest rate, and n is the total number of payments. The formula we get after rearranging to solve for P reflects the initial loan amount or principal based on the monthly payments, interest rate, and the total number of payments.