We have to solve these 4 cases Case 1:Case 2: Case 3: Case 4: and check each in the original to see if it is a solution or whether it is extraneous. Case 1: Check in original: That does not check. so 7 is extraneous. Case 2: Check in original: That checks, so is a solution. Case 3: Check in original: That checks so is a solution. Case 4: Check in original: That does not check, so is extraneous. There are two solutions: and Edwin