Question

Calcule o sétimo termo da PA (3, -1...)

Me ajudem por favor?!

Answer 1

$a1=3\\a2=-1\\an=a1+(n-1).r\\r=a2-a1=-1-3=-4\\a7=3+(7-1).-4\\\boxed{a7=3+-24=\boxed{-21}}$