Question

求函数f(x)=[(1/3!)*A(6,x+2)]/[1+C(3,4)+C(3,5)+.+C(3,x)]最小值

Answer 1

∵[1+C(3,4)+C(3,5)+.+C(3,x)]=c(4,x+1)

∴f(x)=[(1/3!)*A(6,x+2)]/[1+C(3,4)+C(3,5)+.+C(3,x)]=4(x+2)(x-3)

所以当x=1/2是f(x)最小最小值为-25