MCQ
If $(a -2)x^2 + ay^2 = 4$ represents rectangular hyperbola, then $a$ equals :-
  • A
    $0$
  • B
    $2$
  • $1$
  • D
    $3$

Answer

Correct option: C.
$1$
c
We know that for Rectangular Hyperbola, $b^{\prime}=a^{\prime}$ (the general form)

$\Rightarrow$ On simplifying Equation

1, $\frac{x^{2}}{\frac{4}{a-2}}-\frac{y^{2}}{\left(\frac{-4}{a}\right)}=1$

where we see, $a^{2}=\frac{4}{a-2}$ and $b^{2}=\frac{-4}{a}$

If $b^{\prime}=a^{\prime} \Rightarrow b^{\prime 2}=a^{\prime 2}$

$\Rightarrow \frac{-4}{a}=\frac{4}{a-2}$

$\Rightarrow-(a-2)=a$

$\Rightarrow 2=2 a$

$\Rightarrow a=1$

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