Example 32

$\;\;\;(4 + 5x^{4})^2$

$=(A + B)^2 \text{, where } A = 4 \text{ and } B = 5x^{4} $

$=A^2 + 2AB + B^2$

$=(4)^2 + 2(4)(5x^{4}) + (5x^{4})^2 $

$=16 + 40x^{4} +25x^{8} $