The first three terms of a sequence are

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

Problem

5,\;10x,\;20x^{2}

. For the sequence to be a geometric progression with common ratio

2

, the value of

x

must be (a)

\dfrac{1}{4}

(b)

2

(c)

1

(d)

-1