A Review of Algebra

by Romeyn Henry Rivenburg

Ratio and Proportion

Proportionals

• mean,
• third,
• fourth.

Theorems

1. Product of means equals product of extremes.
2. If the product of two numbers equals the product of two other numbers, either pair, etc.
3. Alternation.
4. Inversion.
5. Composition.
6. Division.
7. Composition and division.
8. In a series of equal ratios, the sum of the antecedents is to the sum of the consequents as any antecedent, etc.

Special method of proving four quantities in proportion. Let

etc.

Progressions