에프엑스

f(x) ( Korean: 에프엑스) 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.

2012: SMTown Tour, Electric Shock, and Japanese debut

F(x) participated in SMTown Live World tour in Anaheim at Honda Center on May 20, 2012 and in Hsinchu,Taiwan at Hsinchu County Stadium on June 9, 2012 with their label mates.

It was confirmed that f(x) would be making a comeback in either June or July. However, SM later confirmed on June 5, 2012 that the girls would be releasing a new mini-album titled Electric Shockon music sites such as iTunes on June 10, 2012. On June the 5th, SM Entertainment has released a teaser image of Krystal for their comeback mini-album Electric Shock. On the following day, SM released teaser photos of Victoria and Sulli. On the following day SM released f(x)'s album cover and M! Countdown's teaser images. On the 8th of June, SM released teaser photos of Luna and Amber. Along on that day, they released a video teaser for "Electric Shock".

After releasing a series of teaser images and a MV teaser, f(x) have released their newest EP ‘Electric Shock‘ digitally on June 10, 2012. f(x) began promotions for "Electric Shock" on M.net's M! Countdown on June 14 and also performed "Jet" as part of a special comeback stage. The group performed "Electric Shock" on various music shows such as Music Bank, Music Core and Inkigayo.

The group will begin its Japanese promotions by releasing its hit track Hot Summer in mid-August. The track has already been selected as the CM background song for Uminoie Resort, giving fans in Japan a first listen to the spunky track. On June 27, 2012, f(x) Japanese official website went online. f(x) ended their Electric Shock promotions on July 15, and began preparing for their Japanese debut. Representatives of SM Entertainment had released, “Although we haven’t come out with a definite schedule yet, we will be preparing [f(x)] for their official Japanese debut during the second half of the year.” They continued to ensure Korean fans, “f(x) will be attending to Korean activities occasionally alongside their Japanese activities.” A preview for their debut Japanese single, a remake of their 2011 Korean hit, "Hot Summer", was released on July 31, 2012.