MCQ
If $5{x^2} + \lambda {y^2} = 20$ represents a rectangular hyperbola, then $\lambda $ equals
  • A
    $5$
  • B
    $4$
  • $-5$
  • D
    None of these

Answer

Correct option: C.
$-5$
c
(c) Since the general equation of second degree represents a rectangular hyperbola,

if $\Delta \ne 0,\,\,{h^2} > ab$ and

coefficient of ${x^2} + $ coefficient of ${y^2} = 0$.

Therefore the given equation represents a rectangular hyperbola,

if $\lambda + 5 = 0$ $i.e.$, $\,\lambda = - 5$.

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