Now let me show you the most common mistake students make in simple factorization like these. Here is another expression to be fully factorized: 4xy+6xk. A lot of students will be so distracted by that obvious x that they will forget to look for other factors, they will write x(4y+6k) and move on to the next question. Even if they check their work by multiplying the parenthesis out again they won’t realize they are only half right. Unfortunately they’ve only answer part of the question, they have taken out a common factor but they haven’t taken out the highest common factor so they won’t get full marks. What else needs to be outside the parenthesis? Did you say two? That’s right, well done if you saw that. The answer is 2x(2y+3k).