To solve $\sqrt{x^2-6x+15} - \sqrt{x^2-6x+13} = \sqrt{10} - \sqrt{8}$, the most useful substitution is —

Question

Accepted Answer

$y = x^2 - 6x + 13$

Answer

$y = x^2 - 6x$

Answer

$y = x - 6$

Answer

$y = \sqrt{x}$

To solve x2−6x+15−x2−6x+13=10−8\sqrt{x^2-6x+15} - \sqrt{x^2-6x+13} = \sqrt{10} - \sqrt{8}x2−6x+15​−x2−6x+13​=10​−8​, the most useful substitution is —