Sign in
12thPass logo
New chatPYQ LibraryDoubtsRank report
Sign in to see Recents

Your guest activity stays on this device

Sign in to save progress →
Sign in

Hyperbola question

2019 · 10 Apr · Shift 2 · Q41
Guest · filters and generic practice availableBrowsing as a guest · PYQ filters and generic practice are available. Sign in only for personalised features and saved progress.
  1. PYQ Library
  2. /JEE Main
  3. /Mathematics
  4. /Hyperbola
  5. /2019 · 10 Apr · Shift 2 · Q41

Hyperbola question

2019 · 10 Apr · Shift 2 · Q41

JEE MainMathematicsHyperbolaMCQ+4 / −1
If 5x + 9 = 0 is the directrix of the hyperbola 16x2 – 9y2 = 144, then its corresponding focus is :
  1. A
    (53,0)\left( {{5 \over 3},0} \right)(35​,0)
  2. B
    (5, 0)
  3. C
    (- 5, 0)
  4. D
    (−53,0)\left( { - {5 \over 3},0} \right)(−35​,0)
View written solutionFree

Correct answer: C

  1. Write the hyperbola in standard form

Given: 16x2−9y2=14416x^2-9y^2=14416x2−9y2=144

Divide by 144144144: x29−y216=1\frac{x^2}{9}-\frac{y^2}{16}=19x2​−16y2​=1

So the hyperbola is of the form x2a2−y2b2=1\frac{x^2}{a^2}-\frac{y^2}{b^2}=1a2x2​−b2y2​=1 with a2=9,b2=16⇒a=3, b=4.a^2=9,\quad b^2=16 \Rightarrow a=3,\ b=4.a2=9,b2=16⇒a=3, b=4.

  1. Find the eccentricity

For a hyperbola, c2=a2+b2c^2=a^2+b^2c2=a2+b2 So, c2=9+16=25⇒c=5.c^2=9+16=25 \Rightarrow c=5.c2=9+16=25⇒c=5.

Also, e=ca=53.e=\frac{c}{a}=\frac{5}{3}.e=ac​=35​.

  1. Use the directrix formula

For the hyperbola x2a2−y2b2=1,\frac{x^2}{a^2}-\frac{y^2}{b^2}=1,a2x2​−b2y2​=1, the directrices are x=±ae.x=\pm \frac{a}{e}.x=±ea​.

Now, ae=35/3=95.\frac{a}{e}=\frac{3}{5/3}=\frac{9}{5}.ea​=5/33​=59​.

Hence the directrices are x=±95.x=\pm \frac{9}{5}.x=±59​.

Given directrix: 5x+9=0⇒x=−955x+9=0 \Rightarrow x=-\frac{9}{5}5x+9=0⇒x=−59​ This is the left directrix.

  1. Find the corresponding focus

The foci of the hyperbola are (±c,0)=(±5,0).(\pm c,0)=(\pm 5,0).(±c,0)=(±5,0).

The left directrix x=−95x=-\frac{9}{5}x=−59​ corresponds to the left focus: (−5,0).(-5,0).(−5,0).

  1. Match with options

(−5,0)(-5,0)(−5,0) is Option C.

PreviousNext

More from Hyperbola

  • If a hyperbola has length of its conjugate axis equal to 5 and the distance between its foci is 13, then the eccentricity of the hyperbola is :2019 · MCQ
  • A circle cuts a chord of length 4a on the x-axis and passes through a point on the y-axis, distant 2b from the origin. Then the locus of the centre of this circle, is :2019 · MCQ
  • If the vertices of a hyperbola be at (–2, 0) and (2, 0) and one of its foci be at (–3, 0), then which one of the following points does not lie on this hyperbola?2019 · MCQ
  • If the tangents drawn to the hyperbola 4y2 = x2 + 1 intersect the co-ordinate axes at the distinct points A and B then the locus of the mid point of AB is :2018 · MCQ
  • The locus of the point of intersection of the lines, 2​x−y+42​k=0 and 2​kx+ky−42​=0 (k is any non-zero real parameter), is :2018 · MCQ
  • The locus of the point of intersection of the straight lines, tx − 2y − 3t = 0 x − 2ty + 3 = 0 (t ∈ R), is :2017 · MCQ
  • Let a and b respectively be the semitransverse and semi-conjugate axes of a hyperbola whose eccentricity satisfies the equation 9e2 − 18e + 5 = 0. If S(5, 0) is a focus and 5x = 9 is the corresponding directrix of this hyperbola, then a2 −…2016 · MCQ
  • A hyperbola whose transverse axis is along the major axis of the conic, 3x2​+4y2​=4 and has vertices at the foci of this conic. If the eccentricity of the hyperbola is 23​, then which of the…2016 · MCQ