计算：【2x+1】^2-【2x+1】【-1+2x】
=4x²+4x+1-(-2x+4x^2-1+2x)
=4x²+4x+1+2x-4x^2+1-2x
=4x+2
分解因式：【x+2】【x+3】x^2-4
=(x+2)(x+3)(x+2)(x-2)
=(x+2)^2(x-2)(x+3)