f(x) is a South Korean girl group formed by SM Entertainment in 2009. The name is a play on the mathematical notation for function. The f stands for flower and the x represents the female’s double x chromosome. f(x) strives to be the kind of girl group that can change and adapt to many situations. The group members have also been nicknamed “function girls”. The group made their debut on September 5, 2009 with release of a digital single “La Cha Ta” (stylized as “LA chA TA”). The quintet consists of Victoria, Amber, Luna, Sulli, and Krystal.