Question

已知x≥5/2,则f(x)=[x^2-4x+5]/[2x-4]等于多少,

Answer 1

f(x)=[x^2-4x+5]/[2x-4]

=[(x-2)^2+1]/2(x-2)

=(x-2)/2+1/2(x-2)≥1

(x-2)=1/(x-2)

(x-2)=1

x=3 因为x≥5/2

最小值能达到

所以 f(x)=[x^2-4x+5]/[2x-4]≥1