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A geometric sequence begins

2,6,18,
  1. Find the position of the first term in the sequence which is larger than

    100,000
  2. Find smallest number of terms required for the sum

    2+6+18+

    to exceed

    1,000,000

The nth term of a geometric sequence is given by

un=arn1

You need to find the smallest nN satisfying

2×3n1>100,000