(a+b)(a-b)=a la puterea a 2-b la puterea a 2
(a+b)=a la puterea a 2 + 2*a*b+b la puterea a 2
ex3+2)(3-2)=3 la puterea 2-2la puterea 2=9-4=5 fundita
(a+b)la a doua=a la a doua+2ab+b la a doua.
(a-b) la a doua=a la a doua-2ab+b la a doua.
(a+b+c) la a doua=a la a doua + b la a doua + c la a doua+2ab+2bc+2ac
a la a doua - b la a doua=(a -b)(a + b)
(a+b-c)la a doua=a la a doua + b la a doua - c la a doua+2ab+2bc-2ac
(a-b-c)=a la a doua + b la a doua+c la a doua -2ab+2bc-2ac. ROG fundita.