Question

Find the 12th term of a G.P whose 8th term is $192$ and the common ratio is $2$.

Answer 1

$r=2$

$a_8=a_1(2{)}^{8-1}$

$192=a_1(2{)}^7$

$192=a_1(2{)}^7$

$\frac{192}{2^7}=a_1$

$\frac{192}{2^7}\times 2^{12-1}=a_{12}$

$\frac{192}{2^7}\times 2^{11}=a_{12}$

$a_{12}=192\times 2^4$

$a_{12}=3072$