A) - 4 - 7i
B) 4 + 7i
C) 3 + 7i
D) 7 + 4i
Correct Answer: B
Solution :
[b]:
\[(By\,{{R}_{1}}\to {{R}_{1}}-{{R}_{2}},{{R}_{2}}\to {{R}_{2}}-{{R}_{3}})\] \[=(2+i)\{-4{{i}^{2}}+(-1+2i)\}=(2+i)(4-1+2i)\] \[=(2+i)(3+2i)=4+7i\].
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