Find the centre, eccentricity, foci and directions of the hyperbola x^2 – 3y^2 – 2x = 8
Find the centre, eccentricity, foci and directions of the hyperbola x^2 – 3y^2 – 2x = 8

    \[{{x}^{2}}-\text{ }3{{y}^{2}}-\text{ }2x\text{ }=\text{ }8\]

Given:

The equation

    \[=>\text{ }{{x}^{2}}-\text{ }3{{y}^{2}}-\text{ }2x\text{ }=\text{ }8\]

Let us find the centre, eccentricity, foci and directions of the hyperbola

By using the given equation

    \[{{x}^{2}}-\text{ }3{{y}^{2}}-\text{ }2x\text{ }=\text{ }8\]

    \[{{x}^{2}}-\text{ }2x\text{ }+\text{ }1\text{ }-\text{ }3{{y}^{2}}-\text{ }1\text{ }=\text{ }8\]

So,

    \[{{\left( x\text{ }-\text{ }1 \right)}^{2}}-\text{ }3{{y}^{2}}~=\text{ }9\]

RD Sharma Solutions for Class 11 Maths Chapter 27 – Hyperbola - image 47

Here, center of the hyperbola is

    \[\left( 1,\text{ }0 \right)\]

So, let

    \[x\text{ }-\text{ }1\text{ }=\text{ }X\]

The obtained equation is of the form

RD Sharma Solutions for Class 11 Maths Chapter 27 – Hyperbola - image 48

Where,

    \[a\text{ }=\text{ }3\text{ }and\text{ }b\text{ }=\text{ }\surd 3\]

Eccentricity is given by:

RD Sharma Solutions for Class 11 Maths Chapter 27 – Hyperbola - image 49

Foci: The coordinates of the foci are

    \[\left( \pm ae,\text{ }0 \right)\]

    \[X\text{ }=~\pm ~2\surd 3\text{ }and\text{ }Y\text{ }=\text{ }0\]

    \[X\text{ }-\text{ }1\text{ }=~\pm ~2\surd 3\text{ }and\text{ }Y\text{ }=\text{ }0\]

So,

    \[X=~\pm ~2\surd 3\text{ }+\text{ }1\text{ }and\text{ }Y\text{ }=\text{ }0\]

So,

    \[Foci\text{ }=\text{ }\left( 1~\pm ~2\surd 3,\text{ }0 \right)\]

Equation of directrix are:

RD Sharma Solutions for Class 11 Maths Chapter 27 – Hyperbola - image 50

∴ The

    \[center\text{ }is\text{ }\left( 1,\text{ }0 \right),\text{ }eccentricity\text{ }\left( e \right)\text{ }=\text{ }2\surd 3/3,\]

    \[~Foci\text{ }=\text{ }\left( 1~\pm ~2\surd 3,\text{ }0 \right),\]

    \[Equation\text{ }of\text{ }directrix\text{ }=X\text{ }=\text{ }1\pm 9/2\surd 3\]