Deriving and Applying the Finite Geometric Series Formula

Miacademy & MiaPrep Learning Channel

This comprehensive mathematics lesson guides students through the derivation and application of the finite geometric series formula. The video begins by reviewing why the arithmetic series formula (averaging the first and last terms) fails for geometric series due to the lack of a common difference. It then uses algebraic logic to derive a new formula by multiplying the series sum by the common ratio and subtracting the two equations, effectively eliminating the middle terms to isolate the sum.