X^4+6x^2-27=0 развернутое решение плз

[latex] x^{4} +6 x^{2} -27=0[/latex] [latex]x^{2} =t[/latex] [latex] t^{2} +6t-27=0[/latex] [latex]D= b^{2} -4ac=36-4*1*(-27)=36+108=144>0[/latex](2 корня) [latex] t_{1} = \frac{b+ \sqrt{D} }{2a} = \frac{-6+12}{2} = \frac{6}{2} =3[/latex] [latex] t_{2} = \frac{-b- \sqrt{D} }{2a} = \frac{-6-12}{2} = \frac{-18}{2} =-9[/latex] [latex] x_{1} = t_{2} [/latex] [latex] x_{2} = t_{2} [/latex] [latex] x_{1} =3[/latex] [latex] x_{2} =-9[/latex]