Question

Find the 1st, 4th and 8th terms of the sequence.
A(n)=-5*2^n-1

Answer 1

$a_n=-5\cdot2^{n-1}\\\\a_1=-5\cdot2^{1-1}=-5\cdot2^0=-5\cdot1=-5\\\\a_4=-5\cdot2^{4-1}=-5\cdot2^3=-5\cdot8=-40\\\\a_8=-5\cdot2^{8-1}=-5\cdot2^7=-5\cdot128=-640\\\\Answer:\boxed{a_1=-5;\ a_4=-40;\ a_8=-640}$