將函數(shù)y=log3x的圖象向上平移兩個(gè)單位,得到函數(shù)f(x)的圖像
f(x)=log3(x)+2
x屬于【1,9】時(shí),
函數(shù)y=【f（x）】^2+f(x^2)
=[log3(x)+2]²+log3(x²)+2
=[log3(x)]²+6log3(x)+2
=[log3(x)+3]²-7
當(dāng)x=9時(shí),y取到最大值,ymax=18