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

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