[tex]\bf \textit{difference of squares}
\\ \quad \\
(a-b)(a+b) = a^2-b^2\qquad \qquad
a^2-b^2 = (a-b)(a+b)\\\\
-------------------------------\\\\
%x^4-10x^2+9
x^4-10x^2+9\implies (x^2)^2-10x^2+9\implies (x^2-9)(x^2-1)
\\\\\\
\underline{(x^2-3^2)}(x^2-1^2)\implies \underline{(x-3)(x+3)}(x-1)(x+1)[/tex]
[tex]\bf \textit{keep in mind that }1=1^2=1^3=1^5=1^{10}=1^{1000000}[/tex]
