题目

函数f(x)＝x2＋x－. (1)若定义域为[0,3]，求f(x)的值域； (2)若f(x)的值域为[－，]，且定义域为[a，b]，求b－a的最大值. 答案：∵f(x)＝(x＋)2－， ∴对称轴为x＝－. (1)∵3≥x≥0>－， ∴f(x)的值域为[f(0)，f(3)]，即[－，]； (2)∵x＝－时，f(x)＝－是f(x)的最小值， ∴x＝－∈[a，b]，令x2＋x－＝， 得x1＝－，x2＝， 根据f(x)的图象知b－a的最大值是－(－)＝. He made another wonderful discovery, _________ of great importance to science． [　　] A． which I think is B． which I think it is C． which I think it D． I think which is