Question

дано аn. якщо А5=-12;а7=-16,тоа6=&______​

Answer 1

$\displaystyle\bf\\a_{5} =-12\\\\a_{7} =-16\\\\\\a_{6} =\frac{a_{5} + a_{7} }{2} =\frac{-12-16}{2} =\frac{-28}{2} =-14\\\\\\Otvet \ : \ a_{6} =-14$