Question

el r-ésimo termino de 72, 70, 68, 66.

Answer 1

RESOLUCION:
72,70,68,66,...
72-70=70-68
R=-2
TN=T1+R(N-1)
TN=72-2(N-1)
ESPERO HABERTE AYUDADO

Answer 2

Datos:

a1 = 72
an = 66
d = -2
n = r

${a_n=a_1+(n-1)d}\\\\{a_r=72+(r-1)(-2)}\\\\{a_r=72-2r+2}\\\\{\boxed{a_r=74-2r}}$