Question

in an AP with 18 terms the common difference is -2 if the nth term is 35 what is the first term?​

Answer 1

a18 = a+(18-1)d

35 = a+17(-2)

35 = a-34

35+34 = a

69 = a

First term is 69

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Answer 2

Answer:

an = 18

d = -2

n = 35

an = a + ( n - 1 ) × d

18 = a + ( 35 - 1 ) × (-2)

18 = a + (34 ) × (-2)

18 = a - 68

18 + 68 = a

86 = a

or , a = 86