Expression 4: "f" left parenthesis, "x" , right parenthesis equals cosine left parenthesis, "x" , right parenthesis times cosine left parenthesis, "x" times 2cos left parenthesis, "x" times 0.5 , right parenthesis , right parenthesis times 0.5 plus 1fx=cosx·cosx·2cosx·0.5·0.5+1