Natural Numbers : The numbers use for counting are called Natural Numbers,i.e,1,2,3,4,………..are called natural or counting numbers. It is denoted by N.
Even Numbers: The numbers which are exactly divisible by 2 are called Even numbers.e.g: 2, 4, 6…….
Odd Numbers: The numbers which are not exactly divisible by 2 are called Odd numbers. e.g.: 1, 3, 5, 7…
Factor: A natural number which divides a given number exactly is called a factor of the given number. A factor is also called as divisor. e.g.: 1, 3,5,15 divides 15 exactly. Therefore the factors of 15 are 1, 3,5,15.
Prime Number: The natural numbers which have only one and themselves as factors are called prime numbers. e.g.: 2, 3, 5, 7…
Composite Number: A natural number which is not a prime is called composite number. e.g.: 4, 6, 8, 9, 10, 12……
Real Numbers: The set of real numbers comprising natural numbers, whole numbers, intergers, rational numbers and irrational numbers.
Twin primes: A pair of primes are said to be twin primes if they differ by 2. e.g. : (3,5), (5,7),(17,19),(29,31) are twin primes.
Co-primes: A pair of numbers is said to be co-prime if the numbers have no common factors other than 1. e.g.: (11, 19), (16, 47) are co-primes.
Perfect Number: A number for which the sum of all its factors is twice the number itself is called a perfect number.
Ratio: Comparing similar quantities by division is called ratio.
Compound Ratio: The compound ratio of p: q and r: s is defined as pr: qs. i.e., product of antecedents, product of extremes.
Percentage: Fractions having 100 in the denominator are called percentages; it is denoted by the symbol %.
Marked Price or Catalogue Price: The cost fined by the manufacturers of an article is called Marked Price.
Linear equation: An equation in which the highest index of the variables present is 1 is called a Linear equation. e.g.: 2x+5y
Set: A set is a well-defined collection of objects.
Null or Empty set: A set which don’t have any elements.
Singleton Set: If a set contained only one element is called as Singleton Set
Finite and Infinite Sets: If a set contains finite number of elements it is called finite set otherwise it is infinite set.
Matrix: A matrix is a rectangular array of elements. Generally the elements are numbers.
Square Matrix: In a matrix if the no of rows is equal to the no of columns, it is called a Square matrix
Point: A point has a position. Its location can be ascertained. Points are denoted by capital letters like A, B, C etc.
Line: The basic idea of line is its straightness. It has no end points. It extends indefinitely in both directions.
Collinear points: Points lying on the same line is called collinear points.
Plane: A plane is a flat surface extending indefinitely in all directions.
Line Segment: A line segment is a set of all the points between the end points and also including the end points.
Ray: A ray is a part of line. It has only one initial point. It extends indefinitely in one direction only.
Angle: An angle is the union of two different rays having the same initial point.
Parallel Lines: Two coplanar lines are said to be parallel if they are not intersecting.
Transversal: A line which intersects two or more given lines at different points is called a transversal to the given lines.
Triangle: A simple closed figure bounded by three line segments is called Triangles.
Polygon: A closed plane figure of many sides is called a polygon.
Regular Polygon: A polygon in which all the sides are of equal length is called a Regular Polygon.
Circle: The locus of all the points in a plane equidistant from a given point in the same plane is a circle.
Algebraic Expression: A combination of terms obtained by the operations of + or – or both is called an algebraic expression.
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