For real numbers $a$ and $b$, if $4 a+i(3 a-b)=b-6 i$ and $z=a+\frac{b}{4} i$, then $\frac{|z|}{a}=$
For real numbers $a$ and $b$, if $4 a+i(3 a-b)=b-6 i$ and $z=a+\frac{b}{4} i$, then $\frac{|z|}{a}=$
- $2 \sqrt{2}$
- $6 \sqrt{2}$
- $\sqrt{2}$
- $2$
Solution
$\because 4 a+i(3 a-b)=b-6 i$
Comparing both sides, we get :
$\begin{aligned}
& 4 a=b \\
& 3 a-b=-6 \Rightarrow 3 a-4 a=-6 \Rightarrow, a=6 \\
& \therefore \quad b=24 \\
& Z=a+\frac{b}{4} i \Rightarrow z=6+\frac{24}{4} i=6+6 i \\
& |z|=\sqrt{36+36}=6 \sqrt{2} \\
& \frac{|z|}{a}=\frac{6 \sqrt{2}}{6}=\sqrt{2}
\end{aligned}$
Asked in: AP EAMCET 2023 (17 May Shift 1)
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