[tex](x-1)(x+1) = x^2 - 1[/tex]
Punctele b,c,d sunt asemenea.
[tex](2x+1)(x+2) = 2x^2 +4x + x + 2 = 2x^2 + 5x +2[/tex]
[tex](1-x)(5x-4) = 5x - 4 - 5x^2 + 4 x = -5x^2 + 9x - 4[/tex]
http://tinyurl.com/ku32zd4
[tex](2x-1)(4-x) + (3x+2)(6x-5) =[/tex][tex]( 4x - 2x^2 - 4 + x ) + (18x^2+16x+12x-10)=[/tex][tex]16x^2 + 33x - 14[/tex]
Dacă nu greșesc nimic.
Ține minte - [tex](a+b)(a-b) = a^2 - b^2[/tex]