Use f(x)=x-64 and g(x)=x +64 to find a formula for each expression. Identify its domain. (a) (f+g)(x) (c) (fg)(x) (b) (f-g)(x) (d) (f/g)(x) (a) (f+g)(x) = (Simplify your answer. Do not factor.) Identify its domain. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA {x} (Use a comma to separate answers as needed.) O B. All real numbers (b) (f-g)(x) = (Simplify your answer. Do not factor.) Identify its domain. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. {x} (Use a comma to separate answers as needed.) B. All real numbers (c) (fg)(x) = (Simplify your answer. Do not factor.) Identify its domain. Select the correct choice below and, if necessary, fill in the answer box to complete your choice. OA. {x} (Use a comma to separate answers as needed.)