arcctg(x^3-8x^2+15x+1)=п/4

Question

arcctg(x^3-8x^2+15x+1)=п/4

Answer 1

x^3-8x^2+15x+1=ctg(pi/4)=1
x(x^2-8x+15)=0
x(x-3)(x-5)=0

x=0, x=3, x=5