If sequence a1, a2.........an is such that an= 2(an-1) -x for all
positive integers n>=2 and for certain number x. If a5= 99 and
a3=27, what is the value of x?
a)3
b)9
c)18
d)36
e)42
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Sequence Problem
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Robinmrtha
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we have
an= 2(an-1) -x
we have
a5= 99
or an= 2(an-1) -x
or 99=2a4-x---------------eqn 1
a3=27
or an= 2(an-1) -x
or a4=2a3-x
or a4=54-x
substitute this value is eqn 1
we get x = 3
Ans is A
an= 2(an-1) -x
we have
a5= 99
or an= 2(an-1) -x
or 99=2a4-x---------------eqn 1
a3=27
or an= 2(an-1) -x
or a4=2a3-x
or a4=54-x
substitute this value is eqn 1
we get x = 3
Ans is A
