设X＞1,求函数y=x-1分之2x平方-x+1

题目

设X＞1,求函数y=x-1分之2x平方-x+1

答案

y=(2x^2-x+1)/(x-1),(X＞1)
=[2(x^2-2x+1)+3x-2+1]/(x-1)
=2(x-1)+2/(x-1)+3.
≥2√[2(x-1)*2(x-1)]+3,当且仅当2(X-1)=2/(X-1)时,取等号.
=2*2+3
=7.