Please Explain, Thanks :)

QUESTION 1 Come up with a regular expression for Strings over the alphabet (a,b), which start and end with different symbols. It means, if it starts with 'a it ends with b'; if it starts with 'b', it ends with 'a O a(a+b)'b +b(a+b)'a O a(ab)'b + b(ab)a O a(a+b)'a+ b(a+b)'ab O a (a+b)'b*