[tex]a^{n} -b^{n}=(a-b)[(a^{n-1}b+a^{n-2}\cdot b^{2}b^{3}+.....+a\cdot b^{n-1}][/tex] Formula binomului general
[tex]a) a^{4}-b^{4}=(a^{2} -b^{2})(a^{2} +b^{2}) =(a-b)(a+b)(a^{2} +b^{2} )\\ \\b)a^{5}-b^{5}=\\ \\ a^{n} -b^{n}=(a-b)[(a^{n-1}b+a^{n-2}\cdot b^{2}b^{3}+.....+a\cdotb^{n-1}]\\ \\ a^{5}-b^{5}=(a-b)(a^{4}+a^{3}\cdot b+a^{2}\cdot b^{2} +a\cdot b^{3}+b^{4})[/tex]
