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secondary 3 | A Maths
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2²ⁿ+² x 3²ⁿ / (4 x 9)ⁿ = 9ⁿ+² / 2ⁿ
2²ⁿ+² x 9ⁿ / (2² x 9)ⁿ = 9ⁿ+² / 2ⁿ
2²ⁿ+² x 9ⁿ / (2²ⁿ x 9ⁿ) = 9ⁿ+² / 2ⁿ
2²ⁿ+²-²ⁿ = 9ⁿ+² / 2ⁿ
2² = 9ⁿ+² / 2ⁿ
2² x 2ⁿ = 9ⁿ+²
2ⁿ+² = 9ⁿ+²
Only possibility for n+2 = 0 for this equation to be satisfied (i.e 2^0 = 9^0 = 1)
n + 2 = 0
n = -2
Alternatively,
2ⁿ+² = 9ⁿ+²
Take ln on both sides,
ln 2ⁿ+² = ln 9ⁿ+²
(n+2)ln2 = (n+2)ln9
(n+2)(ln 2 - ln9) = 0
n + 2 = 0 since (ln2 - ln9) is negative
n = -2
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