====== Question 3, Review Exercise ======
Solutions of Question 3 of Review Exercise of Unit 01: Complex Numbers. This is unit of Model Textbook of Mathematics for Class XI published by National Book Foundation (NBF) as Federal Textbook Board, Islamabad, Pakistan. 

===== Question 3(i) =====
Factorize the following: $3 x^{2}+108$

** Solution. **

\begin{align*}
& 3 x^{2}+108\\
=&3 (x^{2}+36)\\
=&3 (x^{2}-(6i)^2)\\
=&3 (x+6i)(x-6i)
\end{align*}
===== Question 3(ii) =====
Factorize the following: $4 x^{2}+40$

** Solution. **

\begin{align*}
&4 x^{2}+40\\
=&4 (x^{2}+10)\\
=&4 (x^{2}+(\sqrt{10}i)^2)\\
=&4 (x+\sqrt{10}i)(x-\sqrt{10}i)
\end{align*}





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