解答:
y=x(x-3)(x-1)(x-2)
=(x²-3x)(x²-3x+2)
令t=x²-3x+1=(x-3/2)²-5/4≥-5/4
所以 t²≥0
所以 y=(t-1)(t+1)=t²-1≥-1
所以,函数y=x(x-1)(x-2)(x-3)的值域【-1,+∞)
y = x(x - 1)(x - 2)(x - 3)
= (x² - 3x)(x² - 3x + 2)
= (x² - 3x)² + 2(x² - 3x) + 1 - 1
= (x² - 3x + 1)² - 1
y ∈[ -1 , +∞ )
=﹙x²-3x﹚﹙x²-3x+2﹚=﹙x²-3x﹚²+2﹙x²-3x﹚+1-1
=﹙x²-3x+1﹚²-1=[﹙x-3/2﹚²-5/4]²-1
﹙x-3/2﹚²-5/4的范围是[-5/4, +∞﹚ ∴[﹙x-3/2﹚²-5/4]²的范围是[0, +∞﹚
∴y的值域[﹣1, +∞﹚
不好意思,太难了,能出简单一点的不