Progression Practice Test 1

Question : 3 of 23

Marks: +1, -0

Find the nth term and 16th term of the sequence -8, 24, -72, .......

Solution:

The given sequence is a GP with a = -8 and r = -3

∴t_n=ar^{n-1}=(-8)(-3)^{n-1}

=(-1)^n(8)×3^{n-1}

For the 16th term putting n = 16
We get

t_16 = (-)^16 \;8 × 3^{16-1 }= 8 × 3^15

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