Question

Уравнение и его корни

Answer 1

х=-5, х=-1, х=1, х=5

Answer 2

$5 x^{4} -130 x^{2} +125=0/:5\\ x^{4} -26 x^{2} +25=0\\ x^{2} =t\\t ^{2} -26t+25=0\\D=676-100=576\\ \sqrt{D} =24\\ t _{1} = \frac{26+24}{2} =25\\t _{2} = \frac{26-24}{2} =1$

$\\ x^{2} =25\\ x_{1} =5\\ x_{2} =-5 \\ \\ x^{2} =1\\ x_{3} =1\\ x_{4} =-1$