Question

S=6^2+6^3+6^4+...+6^102

ai bit giup em voi a

Answer 1

S=6²+6³+....+6¹⁰²

=>6S=6³+6⁴+....+6¹⁰³

=>6S-S=(6³+6⁴+...+6¹⁰³)-(6²+6³+....+6¹⁰²)

=>5S=6¹⁰³-6²

=>\(S=\frac{6^{103}-6^2}{5}\)