Question

помогите решить пример
(х^2-7)^2-8(х^2-7)-9=0

Answer 1

$( x^{2} -7)^{2} -8( x^{2} -7)-9=0 \ ( x^{2} -7)=a \ a^{2} -8a-9=0 \ D= { (-8)^{2}+4*9}= 100= 10^{2} \ a_{1} = frac{8-10}{2} = -1 \ a_{2} = frac{8+10}{2}=9$$x^{2} -7= a \ x^{2} -7=-1 \ x^{2} =6 \ x_{1} =- sqrt{6} \ x_{2} = sqrt{6} \ x^{2} -7=a \ x^{2} -7=9 \ x^{2} =16 \ x_{3}=-4 \ x_{4} =4$