Answer:
l = 13
Step-by-step explanation:
given,
Sum of first 9 term = 135
first term (a) = 17
n = 9
l = a + (n -1)d
l = 17 + (9-1)d
l = 17 + 8 d
[tex]S_n = \dfrac{n}{2}(a+l)[/tex]
[tex]135 = \dfrac{9}{2}(17+17 + 8 d)[/tex]
[tex]135 = {9}\times (17+ 4 d)[/tex]
15 = 17 + 4 d
d = -0.5
now 9 th term
l = 17 + 8 d
l = 17 + 8 × (-0.5)
l = 13
