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Chapter VI review. Review of the Grade 7 algebra course

Lessons 37–38 · 2 lessons · Sh.A. Alimov, O.R. Xolmuhamedov, M.A. Mirzaahmedov. Algebra, Grade 7, revised and expanded 5th edition. O‘qituvchi NMIU, Tashkent, 2017
38

Review of the Grade 7 algebra course

Textbook: pp. 171–179
GoalFinal review of the main topics of the Grade 7 algebra course (expressions, equations, polynomials, factoring, fractions, combinatorics).
New words
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Explanation

During the course we learned to build and simplify algebraic expressions, to solve linear equations in one unknown and word problems with them, to work with powers, monomials and polynomials, to factor polynomials, to operate with algebraic fractions and to use elements of combinatorics. The main formulas are (a ± b)² = a² ± 2ab + b², a² - b² = (a - b)(a + b), a³ ± b³ = (a ± b)(a² ∓ ab + b²), aᵐ · aⁿ = aᵐ⁺ⁿ, Pₙ = n!, Cₙᵏ = n!/(k!(n - k)!). To avoid mixing them up, tell apart the left and right sides: (a - b)² is expanded into a polynomial, while a² - b² is turned into a product. Before an exam, solve one typical task from every chapter.

Worked examples
(x + 3)² - (x - 3)² = x² + 6x + 9 - x² + 6x - 9 = 12x.
(x + 1) : 2 - (x - 1) : 3 = 2. Multiply both sides by 6: 3(x + 1) - 2(x - 1) = 12; 3x + 3 - 2x + 2 = 12; x = 7.
Class activity

“Exam preparation”: the class splits across 6 stations (expressions, equations, polynomials, factoring, fractions, combinatorics). Each group solves one task at a station and moves on. The group with the most correct answers wins.

Practice
1
Compute 3 · 2³ - (-2)².
2
Factor 4x² - 36 completely.
3
Solve (x + 1) : 2 - (x - 1) : 3 = 2.
4
Why are (a - b)² and a² - b² not the same?