Final answer:
Coldplay's first song to hit #1 on both the U.K. and U.S. charts, inspired by Frida Kahlo's last known painting, is 'Viva la Vida'.
Step-by-step explanation:
The song by Coldplay that reached #1 on both the U.K. and U.S. charts and is named after Frida Kahlo's last known painting is 'Viva la Vida'. Frida Kahlo was a renowned Mexican artist known for her captivating self-portraits and art that deeply reflected her own life experiences and Mexican culture. Although the provided reference information shares insights into Kahlo's life and works, such as 'The Two Fridas' and her 1931 self-portrait with Diego Rivera, it doesn't directly link to the music of Coldplay. However, Coldplay's lead singer Chris Martin has acknowledged that the song's name was inspired by Kahlo's painting 'Viva la Vida', meaning "live the life," which embodies the notion of celebrating life despite its hardships. This connects with Kahlo's artistic narrative, which often dealt with personal pain and resilience.