Final answer:
Chas Chandler asked Jimi Hendrix to play guitar and sing backup vocals.
Step-by-step explanation:
The person who asked Jimi Hendrix to play guitar and sing backup vocals is Chas Chandler.
Chas Chandler was the bassist of the British rock band The Animals, and he discovered Jimi Hendrix performing in New York City. Impressed by Hendrix's talent, Chandler invited him to London and became his manager.
Hendrix's tenure as a backup musician was short-lived, as his incredible guitar skills and unique style quickly led him to become a frontman and one of the most influential guitarists in rock history.