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## Question

secondary 4 | A Maths

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Pls help for q1 & q2!

let X be 3ˣ

9ˣ - 15(3ˣ⁻¹) - 14 = 0

3²ˣ - 15(3ˣ/3) - 14 = 0

(3ˣ)² - 5(3ˣ) - 14 = 0

X² - 5X - 14 = 0

(X-7)(X+2) = 0

X = 7 or X = -2

subst. X = 3ˣ ,

3ˣ = 7 or 3ˣ = -2 (n.a.)

x = lg 7/lg 3

= 1.77

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