Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
JEE Main 20199 AprilMorning Shift
Exam
JEE Main
Year
2019
Date
9 April
Shift
Morning Shift
Subject
Mathematics
Chapter
Hyperbola

JEE Main 2019 · 9 April · Morning Shift · Mathematics · Hyperbola

If the line y = mx + 7 3 is normal to the hyperbola x ^ 2 24 - y ^...

If the line y=mx+73y = mx + 7\sqrt{3} is normal to the hyperbola x224−y218=1\dfrac{{x}^{2}}{24} - \dfrac{{y}^{2}}{18} = 1, then a value of mm is:

Options

  1. A52\dfrac{\sqrt{5}}{2}
  2. B35\dfrac{3}{\sqrt{5}}
  3. C152\dfrac{\sqrt{15}}{2}
  4. D25\dfrac{2}{\sqrt{5}}

Correct answer

D. 25\dfrac{2}{\sqrt{5}}

Step-by-step solution

The given equation of the hyperbola is x224−y218=1,\dfrac{{x}^{2}}{24} - \dfrac{{y}^{2}}{18} = 1, which is of the form x2a2−y2b2=1.\dfrac{{x}^{2}}{{a}^{2}} - \dfrac{{y}^{2}}{{b}^{2}} = 1 .

⇒a2=24;b2=18⇒ {a}^{2} = 24; {b}^{2} = 18

We know that the equation of a normal of slope mm to the hyperbola x2a2−y2b2=1\dfrac{{x}^{2}}{{a}^{2}} - \dfrac{{y}^{2}}{{b}^{2}} = 1 is y=mx±m(a2+b2)a2−b2m2y = mx \pm \dfrac{m\left({a}^{2} + {b}^{2}\right)}{\sqrt{{a}^{2} - {b}^{2}{m}^{2}}}

Thus, the equation of the normal to the given hyperbola is y=mx±m(24+18)24−18m2y = mx \pm \dfrac{m\left(24 + 18\right)}{\sqrt{24 - 18{m}^{2}}}

y=mx±m(42)24−18m2y = mx \pm \dfrac{m\left(42\right)}{\sqrt{24 - 18{m}^{2}}}

Given, the normal is y=mx+73y = mx + 7\sqrt{3}

Hence, comparing the two equations, we get 42m24−18m2=73\dfrac{42m}{\sqrt{24 - 18{m}^{2}}} = 7\sqrt{3}

⇒(42m)224−18m2=49×3⇒ \dfrac{{\left(42m\right)}^{2}}{24 - 18{m}^{2}} = 49 \times 3

⇒42×42m2=49×3(24−18m2)⇒ 42 \times 42{m}^{2} = 49 \times 3\left(24 - 18{m}^{2}\right)

⇒12m2=24−18m2⇒ 12{m}^{2} = 24 - 18{m}^{2}

⇒m2=2430=45⇒ {m}^{2} = \dfrac{24}{30} = \dfrac{4}{5}

⇒m=±45=±25.⇒ m = \pm \sqrt{\dfrac{4}{5}} = \pm \dfrac{2}{\sqrt{5}} .

Practice Hyperbola on Quantrex Academy →

More from Hyperbola

If the eccentricity e of the hyperbola (x^2)/(a^2) - (y^2)/(b^2) = 1 , passing through… JEE Main 2026Let the eccentricity e of a hyperbola satisfy the equation 6e^2 - 11e + 3 = 0 . If the… JEE Main 2026Let H: (x^2)/(a^2)-(y^2)/(b^2)=1 be a hyperbola such that the distance between its foci… JEE Main 2026Let O be the origin, and P and Q be two points on the rectangular hyperbola xy = 12 such… JEE Main 2026For some θ ∈(0, (π)/(2)) , let the eccentricity and the length of the latus rectum of the… JEE Main 2026Let PQ be a chord of the hyperbola x^ 2 4 - y^ 2 b^ 2 =1 , perpendicular to the x -axis… JEE Main 2026Let the domain of the function f(x)= _ 3 _ 5 _ 7 (9 x-x^ 2 -13) be the interval (m, n) .… JEE Main 2026Let P(10,2 15 ) be a point on the hyperbola x^ 2 a^ 2 - y^ 2 ~b^ 2 =1 , whose foci are S… JEE Main 2026If the line α x+2 y=1 , where α ∈ ℝ , does not meet the hyperbola x^ 2 -9 y^ 2 =9 , then… JEE Main 2026Let the foci of a hyperbola coincide with the foci of the ellipse x^ 2 36 + y^ 2 16 =1 .… JEE Main 2026Let e_1 and e_2 be the eccentricities of the ellipse x^2 ~b^2 + y^2 25 =1 and the… JEE Main 2025Let the lengths of the transverse and conjugate axes of a hyperbola in standard form be… JEE Main 2025Consider the hyperbola (x^2)/(a^2)-(y^2)/(b^2)=1 having one of its focus at P(-3,0) . If… JEE Main 2025Let the sum of the focal distances of the point P(4,3) on the hyperbola H: x^2 a^2 - y^2… JEE Main 2025If the equation of the hyperbola with foci (4,2) and (8,2) is 3 x^2-y^2-α x+β y+γ=0… JEE Main 2025Let the product of the focal distances of the point P(4,2 3 ) on the hyperbola H: x^2 a^2… JEE Main 2025 Full Hyperbola list Hyperbola JEE Maths PYQsJEE Mathematics PYQs All JEE Main PYQs