If $\dfrac{a}{b} = \dfrac{c}{d}$, then $\dfrac{a^2+b^2}{a^2-b^2}$ also equals—

Question

Accepted Answer

$\dfrac{c^2+d^2}{c^2-d^2}$

Answer

$\dfrac{c^2-d^2}{c^2+d^2}$

Answer

$\dfrac{c-d}{c+d}$

Answer

$\dfrac{cd}{ab}$

If ab=cd\dfrac{a}{b} = \dfrac{c}{d}ba​=dc​, then a2+b2a2−b2\dfrac{a^2+b^2}{a^2-b^2}a2−b2a2+ also equals—