Question

Calcule o 10° termo da PG (7, 21,63,...)

Answer 1

a1 = 7   q = 21/7 = 3
an =a1 . q^n-1
a10 = 7 . 3^10-1
a10 = 7 . 3^9
a10 = 7 . 19683
a10 = 137781

Answer 2

Progressão geométrica

$\mathsf{a_n=a_1*q^{n-1}\rightarrow\begin{cases}\sf a_1=7\\\sf q=3\\\sf n=10\end{cases} }$

$\mathsf{a_{10}=7*3^{10-1} }$

$\mathsf{a_{10}=7*3^9 }$

$\boxed{\boxed{\mathsf{ a_{10}= 137.781}}}$