Question

(х²+4x+3)²+(x²-2x-15)²=36(x+3)²

Answer 1

$(x^2+4x+3)^2+(x^2-2x-15)^2=36(x+3)^2 \\ (x+1)^2(x+3)^2+(x-5)^2(x+3)^2-36(x+3)^2=0 \\ (x+3)^2((x+1)^2+(x-5)^2-36)=0 \\ x+3=0 \\ x_1=-3 \\ (x+1)^2+(x-5)^2-36=0 \\ x^2+2x+1+x^2-10x+25-36=0 \\ 2x^2-8x-10=0|:2 \\ x^2-4x-5=0 \\ x_2=-1 \\ x_3=5$