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QJEEM22Maf6c0: JEE Main 2022 Mathematics - Class 11 JEEM22Maf6c0 Solution: The set of values of k, for which the circle lies inside the…

The set of values of k, for which the circle C:4x2+4y2−12x+8y+k=0C:4{x^2} + 4{y^2} - 12x + 8y + k = 0 lies inside the fourth quadrant and the point (1,−13)\left( {1, - {1 \over 3}} \right) lies on or inside the circle C, is :

Multiple Choice Options

  • A an empty set
  • B (6,659]\left( {6,{{65} \over 9}} \right]
  • C [809,10)\left[ {{{80} \over 9},10} \right)
  • D (9,929]\left( {9,{{92} \over 9}} \right]

Step-by-Step Verified Solution

C:4x2+4y2−12x+8y+k=0C:4{x^2} + 4{y^2} - 12x + 8y + k = 0

∵\because (1,−13)\left( {1, - {1 \over 3}} \right) lies on or inside the C

then 4+49−12−83+k≤04 + {4 \over 9} - 12 - {8 \over 3} + k \le 0

⇒k≤929\Rightarrow k \le {{92} \over 9}

Now, circle lies in 4th quadrant centre ≡(32,−1)\equiv \left( {{3 \over 2}, - 1} \right)

∴\therefore r < 1 \Rightarrow \sqrt {{9 \over 4} + 1 - {k \over 4}} < 1

\Rightarrow {{13} \over 4} - {k \over 4} < 1

\Rightarrow {k \over 4} > {9 \over 4}

\Rightarrow k > 9

∴\therefore k∈(9,929)k \in \left( {9,{{92} \over 9}} \right)

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