Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
4.{\left( {a - b} \right)^7} - 3.{\left( {a - b} \right)^5} + 2.{\left( {a - b} \right)^2}\\
= {\left( {a - b} \right)^2}.\left[ {4.{{\left( {a - b} \right)}^5} - 3.{{\left( {a - b} \right)}^3} + 2} \right]\\
\Rightarrow \left[ {4.{{\left( {a - b} \right)}^7} - 3.{{\left( {a - b} \right)}^5} + 2.{{\left( {a - b} \right)}^2}} \right]:{\left( {a - b} \right)^2}\\
= {\left( {a - b} \right)^2}.\left[ {4.{{\left( {a - b} \right)}^5} - 3.{{\left( {a - b} \right)}^3} + 2} \right]:{\left( {a - b} \right)^2}\\
= 4.{\left( {a - b} \right)^5} - 3.{\left( {a - b} \right)^3} + 2
\end{array}\)
