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numbers and algebraic expressions
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absolute value
function and its properties
linear function
quadratic function
polynomials
rational function
exponential function
logarithm
number sequences
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derivative and integral of functions
trigonometry
plane geometry
analytic geometry
solid geometry
combinatorics
probability
elements of statistics
kropki game
Absolute value of any number is always positive or equals zero. Examples: |4| = 4, |-4| = 4, |0| = 0, |-5| = 5, |1/2| = 1/2. Geometric interpretation of the absolute value. Absolute value of a number is equal distance of this number from zero. Examples. Properties of the absolute value. |x| ≥ 0, |x * y| = |x| * |y|, |x/y| = |x|/|y|, |-x| = x, |x| = |y| ⇔ x = y or x = -y, |x+y| ≤ |x| + |y|, |x-y| = |y-x|.