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The fifth term of an arithmetic sequence is 18, and the sum of the first 32 terms is 1448. Find the ninth term.

Guest Jan 17, 2021

Guest · Answer 1 · 2021-01-17T03:02:16

Sum of arithmetic sequence

Sum₃₂ = n/2 ( 2a₁ + (n-1)d)

= 32/2 (2a₁+ (32-1)d)

1448 = 16 (2a₁ + 31d)

5th term = 18 = a₁+ 4d so a₁ = 18- 4d use this value of a₁ in the red equation above to calculate 'd'

then ninth term will be: 5th term + 4d = 18 + 4(d)