The missing terms in the arithmetic sequence __,__, 5,8,11,__,__,20 are
-1,2,14,17
Given 5,8,11 are 3 consecutive terms
⇒11−8=8=8−5=3 is the common difference
To get the terms prior to 5, subtract 3
i.e., 5-3=2 & 2-3 = -1
To get the terms after 11, add 3
i.e., 11+3 =14 & 14+3 =17