Question

Hey can you please help me posted picture of question

Answer 1

The correct answer is option D

The solution is shown below:

$x^{2} +16 \\ \\ = x^{2} +(4)^{2} \\ \\ = x^{2} -(-1)(4)^{2} \\ \\ = x^{2} -i^{2} (4)^{2} \\ \\ = x^{2} -(4i)^{2} \\ \\ =(x+4i)(x-4i)$