Articles
Quadratic equation: solving with the discriminant and Vieta's theorem
A guide to reducing a quadratic equation to standard form, solving it with the discriminant or Vieta's theorem, and checking the roots independently.
Read more →Common fractions: simplifying, comparing, and the four operations
Rules for simplifying and comparing common fractions, and for addition, subtraction, multiplication, and division — with domain conditions and checked examples.
Read more →Percent problems: calculating a discount, a markup, and a percent of increase
Solving discounts, markups, an inverse price, and successive percent changes by the coefficient method: steps, checks, and an independent exercise.
Read more →Divisibility tests: rules for 2, 3, 4, 5, 9, 10 and 25
Rules for checking whether a number is a multiple of 2, 3, 4, 5, 9, 10 and 25 without performing division, with explanations, worked examples and an analysis of common mistakes.
Read more →EKUB, the greatest common divisor, and EKUK, the least common multiple: rules, the Euclidean algorithm, and examples
Methods for finding EKUB and the least common multiple using prime factorization and the Euclidean algorithm, applying them to practical problems, and checking answers independently.
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