1)(x²+2x)²-2(x²+2x)-3=0. 2)(x²-x+1)(x²-x-7)=65. 3)x^5+x^4+3x^3+2x+2=0.

1. [latex](x^2+2x)^2-2(x^2+2x)-3=0 \\ t^2-2t-3=0 \\ D=4+12=16=4^2 \\ t= \frac{2\pm4}{2} = \left \{ {{t_1=-1} \atop {t_2=3}} \right. \\ \\ x^2+2x=-1 \\ x^2+2x+1=0 \\ (x+1)^2=0 \\ x_1=-1 \\ \\ x^2+2x=3 \\ x^2+2x-3=0 \\ D=4+12=16=4^2 \\ x= \frac{-2\pm4}{2} = \left \{ {{x_2=-3} \atop {x_3=1}} \right. [/latex] ================== 2. [latex](x^2-x+1)(x^2-x-7)=65 \\ t(t-8)=65 \\ t^2-8t-65=0 \\ D=64+260=324=18^2 \\ t= \frac{8\pm18}{2} = \left \{ {{t_1=-5} \atop {t_2=13}} \right. \\ \\ x^2-x+1=-5 \\ x^2-x+6=0 \\ D=1-24=-23 \\ \\ x^2-x+1=13 \\ x^2-x-12=0 \\ D=1+48=49=7^2 \\ x= \frac{1\pm7}{2} = \left \{ {{x_1=-3} \atop {x_2=4}} \right. [/latex] ==================