已知x方-2x=2,求(x+1)的平方+(x+3)(x-3)+(x-3)(x+1)的值.
问题描述：
已知x方-2x=2,求(x+1)的平方+(x+3)(x-3)+(x-3)(x+1)的值.
答
x^2-2x=2,
x^2-2x+1=3,
(x-1)^2=3,
x-1=±√3,x=1±√3.
(x+1)^2+(x+3)(x-3)+(x-3)(x+1)
=[(x+1)^2+(x-3)(x+1)]+(x+3)(x-3)
=2(x+1)(x-1)+(x+3)(x-3)
=2(x^2-1)+(x^2-9)
=3*x^2-11
=3*[(1±√3)^2]-11
=3*(4±2√3)-11
=1±6√3