Ch 1 · Ratio, Proportion, Indices and Logarithms

📘 Core concepts

1. 1Ratio: comparison of two quantities of same kind in simplest form.
2. 2Proportion: equality of two ratios; a:b = c:d ⇒ ad = bc.
3. 3Indices laws: aᵐ · aⁿ = aᵐ⁺ⁿ, aᵐ/aⁿ = aᵐ⁻ⁿ, (aᵐ)ⁿ = aᵐⁿ.
4. 4Logarithms: if aˣ = N then log_a N = x.
5. 5Common log (base 10), natural log (base e).