Question

求函数y=(x+1)(x-1)(x-3)(x-5)+6在[1,5]上的最值及相应的x值

Answer 1

y=[(x+1)(x-5)][(x-1)(x-3)]+6

=[(x²-4x)-5][(x²-4x)+3]+6

=(x²-4x)²-2(x²-4x)-9

x²-4x=(x-2)²-4

1