Let AequalsStartSet Bold a 1 comma Bold a 2 comma Bold a 3 EndSet and BequalsStartSet Bold b 1 comma Bold b 2 comma Bold b 3 EndSet be bases for a vector space V, and suppose Bold b 1 equals 4 Bold a 1 minus 3 Bold a 3, Bold b 2 equals negative Bold a 1 plus Bold a 2, Bold b 3 equals Bold a 1 plus Bold a 2 plus 5 Bold a 3. a. Find the change-of-coordinates matrix from Upper B to Upper A. b. Find left bracket Bold x right bracket Subscript Upper A for Bold x equals Bold b 1 minus 4 Bold b 2 plus 4 Bold b 3.