2 - 16y2 = 144, then..." - Step-by-step solution, answer key, and detailed explanation on MCA Prep."> 2 - 16y2 = 144, then..." - Step-by-step solution, answer key, and detailed explanation on MCA Prep." /> 2 - 16y2 = 144, then..." - Step-by-step solution, answer key, and detailed explanation on MCA Prep." />

Question 25

Mathematics Parabola Hard

If 3x + 4y + k = 0 is a tangent to the hyperbola 9x<sup>2</sup> - 16y<sup>2</sup> = 144, then the value of k is

(A) 0
(B) 1
(C) -1
(D) -3
✓ Correct Answer: Option A Verified Solution

📘 Step-by-Step Solution & Detailed Explanation:

\(9x^2 - 16y^2 = 144 \Rightarrow \frac{x^2}{16} - \frac{y^2}{9} = 1\), so \(a^2 = 16\) and \(b^2 = 9\).

The line is \(y = -\frac{3}{4}x - \frac{k}{4}\), so \(m = -\frac{3}{4}\) and \(c = -\frac{k}{4}\).

Tangency condition: \(c^2 = a^2m^2 - b^2 = 16 \times \frac{9}{16} - 9 = 0\). So \(c = 0\) and \(k = 0\).

(Note: \(k = 0\) gives \(3x + 4y = 0\), which is actually an asymptote of the hyperbola, a "tangent at infinity". Among the options, 0 is the value that satisfies the tangency condition.)

Answer: (A) 0

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