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secondary 3 | A Maths
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I need help with (ii)
I'm stuck at the equation lg(0.001/Io)∧10 = 90. Where do I go from here?
Sub L = 90, I = 10⁻³ ,
90 = 10lg (10⁻³ / I₀)
90 = lg(10⁻³ / I₀)¹⁰
Raise 90 to the power/index
10⁹⁰ = (10⁻³ / I₀)¹⁰
(10⁹)¹⁰ = (10⁻³ / I₀)¹⁰
The two single terms have the same power/index so compare the bases.
10⁹ = 10⁻³ / I₀
I₀ = 10⁻³ / 10⁹
I₀ = 10⁻³⁻⁹
I₀ = 10⁻¹² or 1 / 10¹²
See 2 Answers
90 = 10lg (10⁻³ / I₀)
9 = lg (10⁻³ / I₀)
Raise the base to the power/index,
10⁹ = 10⁻³ / I₀
I₀ = 10⁻³ / 10⁹
I₀ = 10⁻³⁻⁹
I₀ = 10⁻¹² or 1 / 10¹²