Question

Calcule o décimo termo da P.G(1,2,4,8...)

Answer 1

an=a1.q^n-1

a10=1.2^(10-1)

a10=2^9

a10=512

Observe que:

\text{q}=\dfrac{\text{a}_2}{\text{a}_1}=\dfrac{\text{a}_3}{\text{a}_2}=\dfrac{2}{1}=\dfrac{4}{2}=2

Note que:

\text{a}_{\text{n}}=\text{a}_1\cdot\text{q}^{\text{n}-1}

Desta maneira, podemos afirmar que:

\text{a}_{10}=1\cdot2^{10-1}

Logo:

\text{a}_{10}=2^{9}=512