已知{a_n}是公差不为零的等差数列，且a₁=1，a₂是a₁与a₅的等比中项．

（1）求{a_n}的通项公式；

（2）求{a_n}的前n项和S_n．

阅读下面的一段话，判断正误。

    Hello! I'm Lily. I'm nine years old. I'm from the USA. Look! This is my family. My father is a teacher. My mother is a teacher, too. The girl is my sister, Lucy. She's seven years old. She and I are pupils. I like monkeys and she likes pandas.

如图是使用简单机械匀速提升同一物体的四种方式（不计机械自重和摩擦），其中所需动力最小的是（　　）