Question

помогите пожалуйста срочно на фото ​

Answer 1

$\displaystyle\bf\\\left \{ {{b_{5} =\dfrac{1}{6} } \atop {b_{2} =36}} \right. \\\\\\:\left \{ {{b_{1} \cdot q^{4} =\dfrac{1}{6} } \atop {b_{1} \cdot q=36}} \right. \\--------\\q^{3} =\frac{1}{6} :36=\frac{1}{6} \cdot \frac{1}{36} =\frac{1}{216} \\\\\\q=\sqrt[3]{\frac{1}{216} } =\sqrt[3]{\Big(\frac{1}{6} }\Big)^{3} =\frac{1}{6} \\\\\\b_{1} =36:q=36:\frac{1}{6} =36\cdot 6=216\\\\\\S=\frac{b_{1} }{1-q} =\frac{216}{1-\frac{1}{6} } =216:\frac{5}{6} =216\cdot\frac{6}{5} =259,2$