3 years ago

SEQUENCES AND SERIES

Mathematics

1 answer:

Romashka [77]3 years ago

5 0

Answer:

Step-by-step explanation:

As we Know that formula for arithmetic sequence is

$a_n=a_1+(d-1)$

and for geometric sequence is

$a_n=a1*r^(n-1)$

So,

According to given conditions

$a+7d=a*r^5 (i)\\ a+19d=a*r^7 (ii)$

By dividing equation (i) and (ii)

Hence proved that

$r^2=a+19d/a+7d$

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Answer:

copied from InesWalston expert

Money in the bank account after 3 years will be $329.18

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