Question

помогите с 8, умоляю, срочно!!!

Answer 1

$P= b_{15}=b_1q^{14}\\Q=b_{13}=b_1q^{12}\\R=b_7=b_1q^6\\\\P^{-9}*Q^{12}*R^{-3}= \frac{Q^{12}}{P^9*R^{-3}} = \frac{(b_1q^{12})^{12}}{(b_1q^{14})^9*(b_1q^{6})^3 }= \frac{b_1^{12}q^{144}}{b_1^9q^{126}*b_1^3q^{18}}=\\\\= \frac{b_1^{12}q^{144}}{b_1^{12}q^{144}}=1$

Answer 2

!!!!!!.!..!!!!.......!!