Question
Expand $(11a + b)^3 $
Answer
$\;\;\;(11a + b)^3 $
$=(A + B)^3 \text{ , where } A = 11a \text{ and } B= b$
$=A^3 + 3A^2B + 3AB^2 + B^3 $
$=(11a)^3 + 3(11a)^2(b) + 3(11a)(b)^2 + (b)^3 $
$= 1331a^{3} + 3(121a^{2})(b) + 3(11a)(b^{2}) + b^{3} $
$= 1331a^{3} + 363a^{2}b + 33ab^{2} + b^{3} $