JEE MAIN - Mathematics (2022 - 28th June Morning Shift - No. 19)
The number of elements in the set {z = a + ib $$\in$$ C : a, b $$\in$$ Z and 1 < | z $$-$$ 3 + 2i | < 4} is __________.
Answer
40
Explanation
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at line $y=-2$, we have $(5,-2)(6,-2)(1,-2)(0,-2)$ $\Rightarrow 4$ points
at line $y=-1$, we have $(4,-1)(5,-1)(6,-1)(2,-1)$ $(1,-1)(0,-1) \Rightarrow 6$ points
at line $y=0$, we have $(0,0)(1,0)(2,0)(3,0)(4,0)$ $(5,0)(6,0) \Rightarrow 7$ points
at line $y=1$, we have $(1,1),(2,1),(3,1),(4,1),(5,1)$ i.e. 5 points
symmetrically
at line $y=-5$, we have 5 points
at line $y=-4$, we have 7 points
at line $y=-3$, we have 6 points
So Total integral points $=2(5+7+6)+4$
$$ =40 $$
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