Two numbers and are the first and last terms of an arithmetic progression that has…

MATHEMATICS · Single correct · A Level · Mathematics · Sequences and series · Sequences and series

Problem

Two numbers

a

and

b

are the first and last terms of an arithmetic progression that has exactly one term between them. What is the common difference

d

of this progression? (a)

\dfrac{b-a}{3}

(b)

b-a

(c)

\dfrac{b-a}{2}

(d)

\dfrac{a+b}{2}