Đáp án đúng:
Giải chi tiết:\(\left( {a + b} \right)\left( {{a^3} - {a^2}b + a{b^2} - {b^3}} \right) = {a^4} - {b^4}\)\(\begin{array}{l}VP = \left( {a + b} \right)\left( {{a^3} - {a^2}b + a{b^2} - {b^3}} \right)\\\,\,\,\,\,\,\,\,\, = a\left( {{a^3} - {a^2}b + a{b^2} - {b^3}} \right) + b\left( {{a^3} - {a^2}b + a{b^2} - {b^3}} \right)\\\,\,\,\,\,\,\,\, = {a^4} - {a^3}b + {a^2}{b^2} - a{b^3} + b{a^3} - {a^2}{b^2} + a{b^3} - {b^4}\\\,\,\,\,\,\,\,\, = {a^4} - {b^4} = VT\end{array}\)\( \Rightarrow \) Đpcm
