19.已知椭圆x225+y29=1\frac{{x}^{2}}{25}+\frac{{y}^{2}}{9}=125x2+9y2=1与椭圆x225−k+y29−k=1\frac{{x}^{2}}{25-k}+\frac{{y}^{2}}{9-k}=125−kx2+9−ky2=1,则((( )))