Respuesta :
Step-by-step explanation:
[tex]an = a1 + (n - 1)d \\ d = a2 - a1 \\ a1 = 3 \\ a2 = - 15 \\ d = - 15 - 3 = - 18[/tex]
[tex]a13 = 3 + (12) \times ( - 18) \\ a13 = 3 - 216 \\ a13 = - 213[/tex]
the terms of geometric sequence are 3, -15, 75
given,
1st term (a) = 3
second term (t2)=-15
common ratio (r) = t2/t1
=-15/3
=-5
then
t13= ar^n-1
=3×(-5)^13-1
=3×244140625
=3×244140625
=732421875.