Question

numa P.G,temos a5=32 e a8=256.calcule o primeiro termo ea razao dessa P.G

Answer 1

$\begin{matrix}a_8=a_5\cdot q^{8-5}\\\\a_8=a_5\cdot q^3\\\\256=32\cdot q^3\\\\\dfrac{256}{32}=q^3\\\\8=q^3\\\\\sqrt[3]{8}=q\\\\\boxed{q=2}\end{matrix}\qquad\qquad\qquad\qquad\begin{matrix}a_5=a_1\cdot q^{5-1}\\\\a_5=a_1\cdot q^4\\\\32=a_1\cdot2^4\\\\32=a_1\cdot16\\\\\dfrac{32}{16}=a_1\\\\\boxed{a_1=2}\end{matrix}$