The given expression is a quadratic trinomial in the form of ax^2 + bx + c. To factor it, we need to find two binomials that multiply together to give us the original expression. In this case, we can use the FOIL method to expand (3x + 1)(2x + 7) and see if it matches the original expression. When we multiply the first terms (3x)(2x), we get 6x^2. When we multiply the outer terms (3x)(7), we get 21x. When we multiply the inner terms (1)(2x), we get 2x. Finally, when we multiply the last terms (1)(7), we get 7. Combining these terms, we get 6x^2 + 23x + 7, which matches the original expression. Therefore, the answer is (3x + 1)(2x + 7).