Đáp án:
Giải thích các bước giải:
\[\begin{array}{l}
d)\,\,\,\,{({a^2} + 1)^2} - 4{a^2}\\
\,\,\,\,\,\,\,\, = {({a^2} + 1)^2} - {(2a)^2}\\
\,\,\,\,\,\,\,\, = \,\,({a^2} + 1 + 2a)({a^2} + 1 - 2a)\\
\,\,\,\,\,\,\,\, = {(a + 1)^2}.{(a - 1)^2}\\
\begin{array}{*{20}{l}}
{c){\kern 1pt} {\kern 1pt} {x^3} - 3{x^2} - 3x + 1}\\
{{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} = ({x^3} + 1) - (3{x^2} + 3x){\kern 1pt} }\\
{{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} = (x + 1)({x^2} - x + 1) - 3x(x + 1)}\\
{{\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} {\kern 1pt} = (x + 1)({x^2} - x + 1 - 3x)}
\end{array}\\
\,\,\, = (x + 1)({x^2} - 4x + 1)
\end{array}\]
