Giải thích các bước giải:
Ta có:
\(\begin{array}{l}
a,\\
{\left( {x + 2} \right)^2} - \left( {x - 3} \right)\left( {x + 1} \right)\\
= \left( {{x^2} + 4x + 4} \right) - \left( {{x^2} - 2x - 3} \right)\\
= {x^2} + 4x + 4 - {x^2} + 2x + 3\\
= 6x + 7\\
b,\\
\left( {{x^3} - 2{x^2} + 5x - 10} \right):\left( {x - 2} \right)\\
= \left[ {\left( {{x^3} - 2{x^2}} \right) + \left( {5x - 10} \right)} \right]:\left( {x - 2} \right)\\
= \left[ {{x^2}\left( {x - 2} \right) + 5\left( {x - 2} \right)} \right]:\left( {x - 2} \right)\\
= \left( {{x^2} + 5} \right)\left( {x - 2} \right):\left( {x - 2} \right)\\
= {x^2} + 5
\end{array}\)
