suku ke -9 dari barisan 25,19,13...adalah

b = U2 - U1 = 19 - 25 = -6

U9 = a + ( n - 1 ) b
U9 = a + ( 9 - 1 ) b
U9 = 25 + 8 × (-6)
U9 = 25 - 48
U9 = -23

semoga membantu :)

b = U2 - U1 = lg - 25 = -6

Ug=a+(N-1) b

Ug=a -(9-1) b

Ug=25+8×(-6)

Ug=25-48

Ug= -23

{semoga membantu}