Question

当x大于-1时,求f(x)=(x^2-3x+1)/(x+10的值域

Answer 1

f(x)=(x²-3x-4+5)/(x+1)

=[(x-4)(x+1)+5]/(x+1)

=x-4+5/(x+1)

=(x+1)+5/(x+1)+5≥2√[(x+1)*5/(x+1)]+5=2√5+5

值域[2√5+5,+∞)