Verified Solution • 2025–26 Session moderate

QJEEM25Ma4907: JEE Main 2025 Mathematics - Class 11 JEEM25Ma4907 Solution: Let integers be such that . Then the number of all possible…

Let integers a,b∈[−3,3]\mathrm{a}, \mathrm{b} \in[-3,3] be such that a+b≠0\mathrm{a}+\mathrm{b} \neq 0 . Then the number of all possible ordered pairs (a, b), for which ∣z−az+b∣=1\left|\frac{z-\mathrm{a}}{z+\mathrm{b}}\right|=1 and ∣z+1amp;ωamp;ω2ωamp;z+ω2amp;1ω2amp;1amp;z+ω∣=1,z∈C\left|\begin{array}{ccc}z+1 & \omega & \omega^2 \\ \omega & z+\omega^2 & 1 \\ \omega^2 & 1 & z+\omega\end{array}\right|=1, z \in \mathrm{C} , where ω\omega and ω2\omega^2 are the roots of x2+x+1=0x^2+x+1=0 , is equal to _____________ .

Step-by-Step Verified Solution

amp;a,b∈I,−3≤a,b≤3,a+b≠0amp;∣z−a∣=∣z+b∣amp;∣z+1amp;ωamp;ω2ωamp;z+ω2amp;1ω2amp;1amp;z+ω∣=1amp;⇒∣zamp;zamp;zωamp;z+ω2amp;1ω2amp;1amp;z+ω∣=1\begin{aligned}& a, b \in I,-3 \leq a, b \leq 3, a+b \neq 0 \\& |z-a|=|z+b| \\& \left|\begin{array}{ccc}z+1 & \omega & \omega^2 \\\omega & z+\omega^2 & 1 \\\omega^2 & 1 & z+\omega\end{array}\right|=1 \\& \Rightarrow\left|\begin{array}{ccc}z & z & z \\\omega & z+\omega^2 & 1 \\\omega^2 & 1 & z+\omega\end{array}\right|=1\end{aligned}

amp;⇒z∣1amp;1amp;1ωamp;z+ω2amp;1ω2amp;1amp;z+ω∣=1amp;⇒z∣1amp;0amp;0ωamp;z+ω2−ωamp;1−ωω2amp;1−ω2amp;z+ω−ω2∣=1\begin{aligned}& \Rightarrow z\left|\begin{array}{ccc}1 & 1 & 1 \\\omega & z+\omega^2 & 1 \\\omega^2 & 1 & z+\omega\end{array}\right|=1 \\& \Rightarrow z\left|\begin{array}{ccc}1 & 0 & 0 \\\omega & z+\omega^2-\omega & 1-\omega \\\omega^2 & 1-\omega^2 & z+\omega-\omega^2\end{array}\right|=1\end{aligned}

amp;amp;⇒z3=1amp;⇒z=ω,ω2,1amp; Now amp;amp;∣1−a∣=∣1+b∣amp;⇒10 pairs \begin{aligned}&\begin{aligned}& \Rightarrow z^3=1 \\& \Rightarrow z=\omega, \omega^2, 1\end{aligned}\\&\text { Now }\\&\begin{aligned}& |1-\mathrm{a}|=|1+\mathrm{b}| \\& \Rightarrow 10 \text { pairs }\end{aligned}\end{aligned}

Related Learning Resources & Exam Preparation