Question

{аn}арифметический прогрессия а17=2,7 d=0,1. a1=? a21=?

Answer 1

$a_{17}=2,7,;d=0,1\a_{17}=a_1+16dRightarrow a_1=a_{17}-16d=2,7-16cdot0,1=2,7-1,6=1,1\a_{21}=a_1+20d=1,6+20cdot0,1=1,6+2=3,6$