Question

(progresiones geometricas) determina el primer termino si r = 4 y a20 = 2⁴⁰​

Answer 1

an= a1·$r^{n-1}$

r=4.

a20= $2^{40}$

n= 20

$2^{40}$=a1·$4^{19}$

a1= $2^{40}$/$2^{2}$^19

a1= $2^{40}$/$2^{38}$

a1=4