Factorising and expanding

Factorise:

Put into brackets

2x + 10 = 2(x + 5) 

12x - 20 = 4(3x - 5) 

x^2 + 3x = x(x + 3) 

6x^2 + 15x = 3x(2x + 5)

Expand:

Multiply everything inside by whats outside

3(x - 4) = 3x - 12

5(3x +2) = 15x + 10 

x(x - 6) = x^2 - 6x

4x(3x - 5) = 12x^2 - 20x 

(2x - 5) (x + 4) 

Use the square method 

= 2x^2 + 3x - 20 

Expand and simplify

(x + 3) (x + 5) = x^2 + 8x + 15

(x - 3) (x + 5) = x^2 + 2x - 15 

(x + 3) (x - 5) = x^2 - 2x - 15

(x - 3) (x - 5) = x^2 - 8x + 15