Class 8 Mathematics Formula

Class 8 Important Mathematics Formula

 

Extras (RD Sharma)

 

Algebraic Expressions and Identities

 

1.    a^m x aⁿ = a^m+n

 

2.    P x (Q + R) = P x Q + P x R

(Q + R) x P = Q x P + R x P

(P + Q) x (R + S) = P x R + P x S + Q x R + Q x S

 

3.    (a + b)² = a² + b² + 2ab

(a – b)² = a² + b² – 2ab

(a + b) (a – b) = a² – b²

 

Factorization

 

1.    (a² – b²) = (a + b) (a – b)

 

2.    a² + b² + 2ab = (a + b)² = (a + b) (a + b)

a² + b² – 2ab = (a – b)² = (a – b) (a – b)

 

3.    x² + x(a + b) + ab = (x + a) (x + b)

 

Division of Algebraic Expressions

 

1.    Dividend = Divisor x Quotient + Remainder

 

Mensuration

 

1.    Area of trapezium = (½) x (a + b) x h

 

2.    Of Cuboid

Volume = l x b x h

Height = (V / l x b)

Length = (V / b x h)

Breadth = (V / l x h)

 

3.    Volume of a cube = (edge)³ or (side)³

 

4.    Standard units

1m³ = 1000000m³

1m³ = 1000dm³ = 1000L

1dm³ = 1000cm³ = 1000mL

1kL = 1000L = 10⁶cm³ = 1m³

1cm³ = 1000mm³

 

5.    Surface area of a

Cuboid = 2(l x b + b x h + l x h)

Cube = 6 x (Side)²

 

6.    Area of the four walls of a room = 2 x (l + b) x h = Perimeter of the floor x height

 

7.    Standard units

1cm³ = 1000mm³

1m³ = 10⁶cm³

1dm³ = 1000cm³

1m³ = 1000dm³

1km³ = 10⁹m³

1L = 1000mL³

1kL = 1000L = 1m³

 

8.    Volume of a

Cuboid = l x b x h

Cube = (Side)³

 

9.    Surface area of a

Cuboid = 2 x (lb + bh + lh)

Cube = 6 x (Side)²

 

10.Of a Right Circular Cylinder

Volume = (22/7)r²h

Lateral surface area = 2(22/7)rh

Surface area = 2(22/7)r² + 2(22/7)rh + 2(22/7)r (r + h)

 

NCERT Formulas

 

Data Handling

 

1.    Probability of an event = Number of outcomes that make an event / Total number of outcomes of the experiment

 

Algebraic Expressions and Identities

 

1.    Standard identities

(a + b)² = a² + b² + 2ab

(a – b)² = a² + b² – 2ab

(a² – b²) = (a + b) (a – b)

(x + a) (x + b) = x² + x(a + b) + ab

 

Mensuration

 

1.    Area of

Trapezium = (1/2) x (a + b) x h

Rhombus = (1/2) x d₁ x d₂

 

2.    Surface area of

Cuboid = 2(lb + bh + hl)

Cube = 6l²

Cylinder = 2(22/7)r (r + h)

 

3.    Volume of

Cuboid = l x b x h

Cube = l³

Cylinder = (22/7)r²h

 

4.    1cm³ = 1mL

1L = 1000cm³

1m³ = 1000000cm³ = 1000L

 

Exponents and Powers

 

1.    a^m x aⁿ = a^m+n

a^m / aⁿ = a^m-n

(a^m)ⁿ = a^mn

a^m x b^m = (ab)^m

a⁰ = 1

(a/b)^m = (a^m/b^m)

 

Direct and Inverse Proportions

 

1.    Direct Proportion =  (x₁/y₁) = (x₂/y₂)

 

2.    Indirect Proportion = x₁y₁ = x₂y₂ = (x₁/x₂) = (y₁/y₂)