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4-1.Complex numbers
normal
If $|z_1| = 2 , |z_2| =3 , |z_3| = 4$ and $|2z_1 +3z_2 +4z_3| =9$ ,then value of $|8z_2z_3 +27z_3z_1 +64z_1z_2|$ is equal to:-
A
$216$
B
$18$
C
$64$
D
None
Solution
$\left| {{z_1}{z_2}{z_3}\left( {\frac{{2{{\left| {{z_1}} \right|}^2}}}{{{z_1}}} + \frac{{3{{\left| {{z_2}} \right|}^2}}}{{{z_2}}} + \frac{{4{{\left| {{z_3}} \right|}^2}}}{{{z_3}}}} \right)} \right|$
$\left|z_{1}\left\|z_{2}\right\| z_{3} \| 2 \bar{z}_{1}+3 \bar{z}_{2}+4 \bar{z}_{3}\right|$
$2 \times 3 \times 4 \times 9=216$
Standard 11
Mathematics