Question

x平方减2x减1的绝对值,再减2等于零,问x等于多少,（这是一个方程）

Answer 1

|x^2-2x-1|-2=0

x^2-2x-1 =2 or x^2-2x-1 =-2

x^2-2x-3 =0 or x^2-2x+1 =0

(x-3)(x+1)=0 or (x-1)^2=0

x=3 or -1 or 1