题目

句型转换。 （1） There are some pears on the table.（对画线部分提问） on the table? （2） There is a pen and two pencils in his pencil box.（改为否定句）There a pen two pencils in his pencil box. （3） How much is the dress? (改为同义句) the of the dress? 答案：【1】What【2】is 【1】isn't【2】or 【1】What's【2】price已知a，b∈R，可以证明：(1)12a2+12b2≥(12a+12b)2；(2)13a2+23b2≥(13a+23b)2；(3)14a2+34b2≥(14a+34b)2；根据上述不等式，写出一个更一般的结论，并加以证明．