試證明函數(shù)y=x+1/x在(1,+oo)上為增函數(shù)
試證明函數(shù)y=x+1/x在(1,+oo)上為增函數(shù)
數(shù)學人氣:882 ℃時間:2020-05-05 05:11:30
優(yōu)質(zhì)解答
y'=1-1/x^2=(x^2-1)/x^2
x在(1,+oo)上
x^2>0 x^2-1>0 所以y'>0
所以函數(shù)y=x+1/x在(1,+oo)上為增函數(shù)你是高幾,這是求導數(shù),利用導數(shù)求證函數(shù)的單調(diào)性證明:設(shè)x1,x2屬于(1,+oo) x11,x2>1 x1x2>1x1