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4-1.Complex numbers
medium
यदि $(1 + i)(1 + 2i)(1 + 3i).....(1 + ni) = a + ib$, तब $2.5.10....$$(1 + {n^2})$=
A
${a^2} - {b^2}$
B
${a^2} + {b^2}$
C
$\sqrt {{a^2} + {b^2}} $
D
$\sqrt {{a^2} - {b^2}} $
Solution
(b) हमें ज्ञात है $(1 + i)(1 + 2i)(1 + 3i)…..(1 + ni) = a + ib$ …..$(i)$
= $(1 – i)(1 – 2i)(1 – 3i)…..(1 – ni) = a – ib$…..$(ii)$
$ (i)$ एवं $(ii)$ को गुणा करने पर
$2.5…..(1+ {n^2}) = {a^2} + {b^2}$
Standard 11
Mathematics