Whats the missing term in the geometric sequence 2, __, 50?

1 Answer
Edric Y.
Nov 7, 2015

#10#

Explanation:

In a geometric sequence you multiply by some number #r# to get to the next term. So if we call our missing term #x# we know this:
#2*r = x#
#x * r = 50#

substitute...
#2*r *r = 50#

You could also think of each step in the sequence as multiplying by another #r#, so basically your first term times #r# and times #r# again gives you 50. or #2r^2 = 50#

Either way will get you there.
solve for r...
#2r^2 = 50#
#r^2 = 25#
#r= 5#
Not done just yet...
plug in #r# into one of the above equations...
#2*r = x#
#2*5 = x#
#10 = x#

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