Topics
Integers
- Concept for Natural Numbers
- Concept for Whole Numbers
- Negative and Positive Numbers
- Concept of Integers
- Representation of Integers on the Number Line
- Concept for Ordering of Integers
- Addition of Integers
- Addition of Integers on Number line
- Subtraction of Integers
- Properties of Addition and Subtraction of Integers
- Multiplication of a Positive and a Negative Integers
- Multiplication of Two Negative Integers
- Product of Three Or More Negative Integers
- Closure Property of Multiplication of Integers
- Commutative Property of Multiplication of Integers
- Associative Property of Multiplication of Integers
- Distributive Property of Multiplication of Integers
- Multiplication of Integers with Zero
- Multiplicative Identity of Integers
- Making Multiplication Easier of Integers
- Division of Integers
- Properties of Division of Integers
Fractions and Decimals
- Concept of Fractions
- Types of Fraction
- Concept of Proper Fractions
- Improper Fraction and Mixed Fraction
- Concept for Equivalent Fractions
- Like and Unlike Fraction
- Comparing Fractions
- Addition of Fraction
- Subtraction of Fraction
- Multiplication of a Fraction by a Whole Number
- Fraction as an Operator 'Of'
- Multiplication of a Fraction by a Fraction
- Division of Fractions
- Concept for Reciprocal of a Fraction
- Concept of Decimal Numbers
- Multiplication of Decimal Numbers
- Multiplication of Decimal Numbers by 10, 100 and 1000
- Division of Decimal Numbers by 10, 100 and 1000
- Division of a Decimal Number by a Whole Number
- Division of a Decimal Number by Another Decimal Number
Data Handling
Simple Equations
Lines and Angles
- Concept of Points
- Concept of Line
- Concept of Line Segment
- Concept of Intersecting Lines
- Concept of Angle - Arms, Vertex, Interior and Exterior Region
- Complementary Angles
- Supplementary Angles
- Adjacent Angles
- Concept of Linear Pair
- Concept of Vertically Opposite Angles
- Concept of Intersecting Lines
- Parallel Lines
- Pairs of Lines - Transversal
- Pairs of Lines - Angles Made by a Transversal
- Pairs of Lines - Transversal of Parallel Lines
- Checking Parallel Lines
The Triangle and Its Properties
- Concept of Triangles - Sides, Angles, Vertices, Interior and Exterior of Triangle
- Classification of Triangles (On the Basis of Sides, and of Angles)
- Equilateral Triangle
- Isosceles Triangles
- Scalene Triangle
- Acute Angled Triangle
- Obtuse Angled Triangle
- Right Angled Triangle
- Median of a Triangle
- Altitudes of a Triangle
- Exterior Angle of a Triangle and Its Property
- Angle Sum Property of a Triangle
- Some Special Types of Triangles - Equilateral and Isosceles Triangles
- Sum of the Lengths of Two Sides of a Triangle
- Right-angled Triangles and Pythagoras Property
Congruence of Triangles
Comparing Quantities
- Concept of Ratio
- Concept of Equivalent Ratios
- Concept of Proportion
- Concept of Unitary Method
- Concept of Percent and Percentage
- Converting Fractional Numbers to Percentage
- Converting Decimals to Percentage
- Converting Percentages to Fractions
- Converting Percentages to Decimals
- Estimation in Percentages
- Interpreting Percentages
- Converting Percentages to “How Many”
- Ratios to Percents
- Increase Or Decrease as Percent
- Concepts of Cost Price, Selling Price, Total Cost Price, and Profit and Loss, Discount, Overhead Expenses and GST
- Profit or Loss as a Percentage
- Concept of Principal, Interest, Amount, and Simple Interest
Rational Numbers
- Rational Numbers
- Equivalent Rational Number
- Positive and Negative Rational Numbers
- Rational Numbers on a Number Line
- Rational Numbers in Standard Form
- Comparison of Rational Numbers
- Rational Numbers Between Two Rational Numbers
- Addition of Rational Number
- Subtraction of Rational Number
- Multiplication of Rational Numbers
- Division of Rational Numbers
Practical Geometry
- Construction of a Line Parallel to a Given Line, Through a Point Not on the Line
- Construction of Triangles
- Constructing a Triangle When the Length of Its Three Sides Are Known (SSS Criterion)
- Constructing a Triangle When the Lengths of Two Sides and the Measure of the Angle Between Them Are Known. (SAS Criterion)
- Constructing a Triangle When the Measures of Two of Its Angles and the Length of the Side Included Between Them is Given. (ASA Criterion)
- Constructing a Right-angled Triangle When the Length of One Leg and Its Hypotenuse Are Given (RHS Criterion)
Perimeter and Area
- Mensuration
- Concept of Perimeter
- Perimeter of a Rectangle
- Perimeter of Squares
- Perimeter of Triangles
- Perimeter of Polygon
- Concept of Area
- Area of Square
- Area of Rectangle
- Triangles as Parts of Rectangles and Square
- Generalising for Other Congruent Parts of Rectangles
- Area of a Triangle
- Area of a Parallelogram
- Circumference of a Circle
- Area of Circle
- Conversion of Units
- Problems based on Perimeter and Area
- Problems based on Perimeter and Area
Algebraic Expressions
- Algebraic Expressions
- Terms, Factors and Coefficients of Expression
- Like and Unlike Terms
- Types of Algebraic Expressions as Monomials, Binomials, Trinomials, and Polynomials
- Addition of Algebraic Expressions
- Subtraction of Algebraic Expressions
- Evaluation of Algebraic Expressions by Substituting a Value for the Variable.
- Use of Variables in Common Rules
Exponents and Powers
- Concept of Exponents
- Multiplying Powers with the Same Base
- Dividing Powers with the Same Base
- Taking Power of a Power
- Multiplying Powers with Different Base and Same Exponents
- Dividing Powers with Different Base and Same Exponents
- Numbers with Exponent Zero, One, Negative Exponents
- Miscellaneous Examples Using the Laws of Exponents
- Decimal Number System Using Exponents and Powers
- Expressing Large Numbers in the Standard Form
Symmetry
Visualizing Solid Shapes
- Plane Figures and Solid Shapes
- Faces, Edges and Vertices
- Nets for Building 3-d Shapes - Cube, Cuboids, Cylinders, Cones, Pyramid, and Prism
- Drawing Solids on a Flat Surface - Oblique Sketches
- Drawing Solids on a Flat Surface - Isometric Sketches
- Visualising Solid Objects
- Viewing Different Sections of a Solid
notes
Properties of Addition and Subtraction of Integers:
1. Closure under Addition:
We have learned that sum of two whole numbers is again a whole number. For example, 17 + 24 = 41 which is again a whole number. We know that this property is known as the closure property for the addition of the whole numbers.
Statement |
Observation |
17 + 23 = 40 | Result is an integer |
(- 75) + 18 = - 57 | Result is an integer |
27 + (- 27) = 0 | Result is an integer |
( - 20) + 0 = - 20 | Result is an integer |
(– 35) + (– 10) = - 45 | Result is an integer |
Since the addition of integers gives integers, we say integers are closed under addition.
In general, for any two integers a and b, a + b is an integer.
2. Closure under Subtraction:
We have learned that the subtraction of two whole numbers is again a whole number. For example, 17 - 24 = - 7 which is again a whole number. We know that this property is known as the closure property for the subtraction of the whole numbers.
Statement |
Observation |
7 - 9 = - 2 | Result is an integer |
( -21) - ( -10) = - 11 | Result is an integer |
32 - ( -17) = 49 | Result is an integer |
( -18) - (-18) = 0 | Result is an integer |
(- 29) - 0 = - 29 | Result is an integer |
As you can see that the subtraction of two integers will always be an integer, hence integers are closed under subtraction.
Thus, if a and b are two integers then a – b is also an integer.
3. Commutative Property:
We know that 3 + 5 = 5 + 3 = 8, that is, the whole numbers can be added in any order. In other words, addition is commutative for whole numbers.
Similarly,
(i) (– 8) + (– 9) and (– 9) + (– 8) = - 17
So, (– 8) + (– 9) = (– 9) + (– 8).
(ii) (– 23) + 32 and 32 + (– 23) = 9
So, (– 23) + 32 = 32 + (– 23).
(iii) (- 47) + 0 and 0 + ( - 47) = - 47
So, (- 47) + 0 = 0 + ( - 47).
Thus, Integers can be added in any order.
In other words, addition is commutative for integers i.e., a + b = b + a for all integers a, and b.
- Consider the integers 5 and (– 3).
Is 5 – (– 3) the same as (– 3) – 5?
No, because 5 – (– 3) = 5 + 3 = 8, and (– 3) – 5= – 3 – 5 = – 8.
We conclude that subtraction is not commutative for integers.
4. Associative Property:
Consider the integers – 3, – 2, and – 5.
Look at (– 5) + [(– 3) + (– 2)] and [(– 5) + (– 3)] + (– 2).
In the first sum (– 3) and (– 2) are grouped together and in the second (– 5) and (– 3) are grouped together. We will check whether we get different results.
In both cases, we get – 10. i.e., (– 5) + [(– 3) + (– 2)] = [(– 5) + (– 2)] + (– 3)
Addition is associative for integers, i.e., (a + b) + c = a + (b + c) for all integers a, b and c.
5. Additive Identity:
When we add zero to any whole number, we get the same whole number. Zero is an additive identity for whole numbers. For example, 0 + 59 = 59, 0 + 37 = 37.
Similarly, When we add zero to any integer number, we get the same integer number. Zero is an additive identity for an integer number.
Statement |
Observation |
( - 23) + 0 = - 23 | Result is an integer |
- 61 + 0 = - 61 | Result is an integer |
56 + 0 = 56 | Result is an integer |
0 + 0 = 0 | Result is an integer |
Integer 0 is the identity under addition. That is, a + 0 = 0 + a = a for every integer a.