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a = 4Q. For the GP 4,6,9.... find the value of n if the nth term is the first term greater than 100.
Help me plzz
r = 1.5
nth term = 100
a [1.5^(n - 1)] = 100
4[1.5^(n - 1)] = 100
1.5^(n - 1) = 100/4
1.5^(n - 1) = 25
TAking ln of both sides
(n - 1) ln1.5 = ln25
n - 1 = ln25 / ln1.5
n - 1 = 7.94
n = 8.94
Round it off
n = 9