Question

Give a geometric progression an, whose first term is 15 and common ratio r=-4. Find its sixth term.​

Answer 1

Answer:

Step-by-step explanation:

a= 15

r= - 4

Since aₓ = ar×⁻¹

Hence a₆ = ar⁵ = 15 * 4⁵ = 15*1024 = 18060

Answer 2

Given ,

First term (a) = 15

Common ratio (r) = -4

We know that , the nth term of an geometric progression (GP) is given by

$\boxed{ \tt{a_{n} = a{(r)}^{n - 1} }}$

Thus ,

$\tt \implies a_{6} =15 \times {( - 4)}^{6 - 1}$

$\tt \implies a_{6} =15 \times {( - 4)}^{5}$

$\tt \implies a_{6} = 15 \times ( - 1024)$

$\tt \implies a_{6} = - 15360$

Hence , the sixth term of GP is -15360