Final answer:
The student made an error in the placement of the multiplication sign. The correct answer should be 6x² + 2x².
Step-by-step explanation:
The student's error in factoring the GCF can be identified in the given problem: 6x + 2x² 2x ( 3x + x). The issue lies in the incorrect placement of the multiplication sign between 2x and the parentheses (3x + x). To correctly factor out the GCF, we need to distribute the 2x to both terms inside the parentheses. The correct answer should be: 2x(3x) + 2x(x) = 6x² + 2x².