Please clarify this string method

Beginner in python

x = “data science is powerful”
print(x.strip().upper().title().replace(“POWERFUL”, “AWESOME”))
output - Data Science Is Powerful

print(x.strip().title().replace(“POWERFUL”, “AWESOME”))
output - Data Science Is Powerful

print(x.strip().upper().replace(“POWERFUL”, “AWESOME”))
output - DATA SCIENCE IS AWESOME

why in the 1st and 2nd print output did not work but 3rd print worked?

please explain