If are three numbers in arithmetic progression

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

Problem

x, y, z

are three numbers in arithmetic progression, which of the following relations must be true? (a)

y^{2}=xz

(b)

z-y=x-y

(c)

y=\dfrac{x+z}{2}

(d)

y-x = z-x