Q. The set of values of ‘$c$’ so that the equation $y = |x| + c$ and $x^{2} + y^{2} - 8|x| - 9 = 0$ have no solution, is

A) $( - \infty,\ - 3) \cup (3,\ \infty)$
B) $( - 3,\ 3)$
C) $\left( - \infty,\ 5\sqrt{2} \right) \cup (5\sqrt{2},\ \infty)$
D) $(5\sqrt{2} - 4,\ \infty)$
Explanation

(d)
Since, $y = |x| + c$ and $x^{2} + y^{2} - 8|x| - 9 = 0$ both are symmetrical about $y$-axis for$x > 0,\ y = x + c$. Equation of tangent to circle $x^{2} + y^{2} - 8x - 9 = 0$ which is parallel to $y = x + c$ is $y = (x - 4) + 5\sqrt{1 + 1}$
$\Rightarrow y = x + (5\sqrt{2} - 4)$
For no solution $c > 5\sqrt{2} - 4$,
$\therefore c \in \left( 5\sqrt{2} - 4,\ \infty \right)$

Dr. Abubacker
Reviewed by Dr. Abubacker

Physics Educator & NEET/JEE Specialist

Ph.D. in Physics with 19+ years of teaching experience.

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