Answer
$9;-2$
Work Step by Step
$\ln \left( 7-x\right) +\ln \left( 1-x\right) =\ln \left( 25-x\right) \Rightarrow \ln \left[ \left( 7-x\right) \left( 1-x\right) \right] =\ln \left( 25-x\right) $
$\Rightarrow \ln \left( 7-8x+x^{2}\right) =\ln \left( 25-x\right) \Rightarrow x^{2}-8x+7=25-x\Rightarrow x^{2}-7x-18=0$
$x_{1,2}=\dfrac {-b\pm \sqrt {b^{2}-4ac}}{2a}=\dfrac {7\pm \sqrt {49-4\times 1\times \left( -18\right) }}{2}=\dfrac {7\pm 11}{2}=9;-2$