Question

1+a+ a^{2} + a^{3} +.........+ a^{n} =
EGAL CU ? VA ROGG

Answer 1

1 + a + a^2 + a^3 + ... + a^n = $1 + a^{ \frac{(1+n)*n}{2} } = 1 + a^{ \frac{n + n^{2} }{2} }$