Question

Am nevoie de ajutor cu acest exercitiu!

Answer 1

$\displaystyle b_2=3,~\frac{b_1}{b_4} =\frac{1}{8} ,~b_1=?\\\\ b_n=b_1 \cdot q^{n-1}\\\\ b_2=3 \Rightarrow b_1 \cdot q^{2-1} =3 \R \Rightarrow b_1 \cdot q=3 \Rightarrow b_1=\frac{3}{q} \\\\ \frac{b_1}{b_4} =\frac{1}{8} \Rightarrow \frac{b_1}{b_1 \cdot q^{4-1}}=\frac{1}{8}\Rightarrow \frac{b_1}{b_1\cdot q^3} =\frac{1}{8} \Rightarrow \frac{1}{q^3} =\frac{1}{8} \Rightarrow q^3=8 \Rightarrow q=\sqrt[3]{8} \Rightarrow\\\\\Rightarrow q=\sqrt[3]{2^3}\Rightarrow q=2\\\\b_1=\frac{3}{q} \Rightarrow b_1=\frac{3}{2}$