5. Select equivalent expressions AND solve. x^{4}+5 x^{2}+3=x^{2}-1 \left(x^{2}+6\right)\left(x^{2}-2\right)=0 \left(x^{2}+2\right)^{2}=0 [x=-\sqrt{2}, x=\sqrt{2}, x=-i \sqrt{6}, x=i \sqrt{6}] \text { D }\left(x^{2}+6\right)(x-3)=0 \text { E } x^{3}-3 x^{2}+6 x-18=0 [x=-i \sqrt{2}, x=i \sqrt{2}] \text { G } x^{4}+4 x^{2}+4=0

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