#### Answer

$r=-2;a_{1}=4$

#### Work Step by Step

$\dfrac {a_{m}}{a_{n}}=r^{m-n}\Rightarrow \dfrac {a_{7}}{a_{2}}=r^{5}\Rightarrow \dfrac {256}{-8}=r^{5}=-32\Rightarrow r=-2;a_{2}=a_{1}xr\Rightarrow -8=a_{1}\times \left( -2\right) \Rightarrow a_{1}=4$

Published by
Pearson

ISBN 10:
013421742X

ISBN 13:
978-0-13421-742-0

$r=-2;a_{1}=4$

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