Question

a=3.5 ,d=-3 ,an=99 ,n=?​

Answer 1

Answer:

$a = 3 \\ d = - 3 \\ an = 99 \\ an = a + (n - 1)d \\ 99 = 3 + (n - 1) - 3 \\ 99 = 3 + ( - 3n) + 3 \\ 99 = 6 - 3n \\ 99 - 6 = - 3n \\ 93 = - 3n \\ n = - 31$

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