This is a geometrical presentation of the formula[br]The difference between the areas of the [i][b]a[/b][/i]-sided and the [i][b]b[/b][/i]-sided squares equals the area of the rectangle whose sides are [i][b](a+b)[/b][/i] and [i][b](a-b)[/b][/i].[br]The sliders allow to check it as [i][b]a[/b][/i] and [i][b]b[/b][/i] change

Dragging the siliders you can see that it works for differnt values of [i][b]a[/b][/i] and [b]b[/b][i][/i][b][/b][br][br]1. -Apply the formula to write directly the result, without multiplying term to term :[br]a) (x+2)·(x-2)=[br]b) (3x-1)·(3x+1)=[br]c) [math](2x^2-5x)·(2x^2+5x)=[/math][br]d) [math](3x^3y-4y^2)·(3x^3y-4y^2)=[/math][br][br]2.- Identify the squares and factor the expression [br]e) [math]x^2-9=[/math][br]f) [math]9x^2-1=[/math][br]g) [math]4x^6-9y^2=[/math][br]h) [math]25-4y^8=[/math]