y = −0.5x + 4 and passes through the point A (−6, 5);
(b) perpendicular to the line y = −1.5x + 3 and passes through
the point A (9, 2).
• Prove that the three points (−2, −14), (2, 6), and (3, 11) lie on
the same line. (Dorofeev and Suvorova, 2009a, pp. 188–189)
• The parabola y = ax
2
+ bx + c passes through the points
M (0, 1), K (
−1, 0), and L (1, 4). Determine whether it passes
through the point A (
−4, −5).
• The parabola y = ax
2
+ bx + c passes through the points
M (0,
−2), K (6, 0), and L (3, −4). Find the coordinates of
its vertex. (2009b, p. 161)
Inequalities. The quantity of material connected with inequalities
in basic school is relatively small. All of the textbooks go over the
properties of numerical inequalities and the algorithm for solving linear
inequalities, which is based on these properties. Systems of linear
inequalities are examined with the help of schematic representations
of the solution sets of these inequalities on the number line. The prop-
erties of numerical inequalities are also used to solve problems involving
proofs (for example, to prove such propositions as “the arithmetic mean
of two numbers is not less than their geometric mean” or “the half-
perimeter of a triangle is greater than any of its sides”) and problems
on comparing numbers (for example, compare
√
99
+
√
101
and 20).
In addition to solving linear inequalities and systems of linear
inequalities, in connection with studying quadratic functions, students
solve inequalities of the form ax
2
+ bx + c > 0, where a = 0. The
essence of the technique used to solve such inequalities lies in the fact
that the answer is simply read off a schematically represented graph.
No special rules are formulated. Inequalities are also used for solving
problems from other sections of the course. Consider the following
examples:
1. Find the domain of the expression
√
4
−2x
x+2
.
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2. Find all integer values of m for which the equation
4mx
2
+ 5x + m = 0
has two roots.
3. Find the sum of all positive terms of an arithmetic progression that
begins in the following way: 6.3; 5.8; 5.3; … .
Word problems. Considerable attention is traditionally devoted in
Russian schools to using the algebraic method to solve word problems.
These problems are systematically introduced into the course as the
apparatus of equations develops. They are seen as an effective didactic
instrument for achieving a number of goals. The main ones among
these are:
• Developing the logical thinking of adolescents;
• Demonstrating the possible uses of the algebraic apparatus that
is being formed;
• Acquainting students of ages 12–15 with the idea of mathematical
modeling on a level that is accessible to them;
• Enriching the educational material with themes that are close,
understandable, and interesting to the students, which help to
motivate the students.
Although solving word problems, as has already been indicated,
figures extensively in the course, this form of activity turns out to be
quite difficult and time-consuming for most students. The authors of
the modern generation of textbooks, Dorofeev et al., have revised the
approach to the content and organization of systems of exercises. They
single out as a special form of activity the formulation of equations
based on the conditions given in a problem; students acquire experience
in formulating different equations on the basis of the same conditions
and in determining which of the formulated equations is more conve-
nient for obtaining an answer to the question posed in the problem.
It is important for the students to recognize the necessity of
interpreting the numbers obtained by solving an equation or system of
equations. Consider the following examples of problems on “Quadratic
Equations” for a class working with the textbook of Dorofeev,
Suvorova et al. (2009a, pp. 120–122).
The students are given three problems:
1. A baking sheet must be made out of a rectangular sheet of tin by
cutting out squares in the corners and turning up the edges. The
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