Find the values of a and b for which the sequence $2 , a , b , 17 , \ldots$ is arithmetic
A) $a = 7 , b = 12$
B) $a = 6 , b = 12$
C) $a = 8 , b = 12$
D) $a = 10 , b = 12$
E) $a = 8 , b = 15$

Question

Quizplus · Accepted Answer

In an arithmetic sequence, the difference between consecutive terms is constant. The difference between 17 and b must be the same as the difference between b and a, and also the same as the difference between a and 2. Solving for a and b with these conditions gives $a = 7$ and $b = 12$.

Find the Values of a and B for Which the Sequence