Answer
$1.8,2.2$ and $2.6$
Work Step by Step
Each term is $0.4$ more than the previous term. So, the common difference is $0.4$.
Add $0.4$ to a term to find the next term.
The next three terms are $(1.4+0.4), (1.4+0.4+0.4), (1.4+0.4+0.4+0.4)$.
That is, $1.8,2.2$ and $2.6$.