定義在R上的函數(shù)f(x)和g(x)的導(dǎo)函數(shù)分別為f′(x),g′(x),則下面結(jié)論正確的是( )
①若f′(x)>g′(x),則函數(shù)f(x)的圖象在函數(shù)g(x)的圖象上方;
②若函數(shù)f′(x)與g′(x)的圖象關(guān)于直線x=a對(duì)稱,則函數(shù)f(x)與g(x)的圖象關(guān)于點(diǎn)(a,0)對(duì)稱;
③函數(shù)f(x)=f(a-x),則f′(x)=-f′(a-x);
④若f′(x)是增函數(shù),則f(
)≤
.