What is the greatest common factor for each group?

Answer:
Left group: [tex]2x^{5\\}[/tex] Right group: 3
Step-by-step explanation:
Right group: 3.x - 21 = 3.x - 3.7 = 3 . ( x - 7 )
21 is equal 3 times 7. When we do this change, it is clear which is the common factor, which is just the number 3.
Left group: 2[tex]x^{6\\}[/tex] + 14[tex]x^{5\\} \\[/tex] = 2[tex]x^{5\\}[/tex].x + 2[tex]x^{5}[/tex].7 = 2[tex]x^{5\\}[/tex] . (x + 7)
Explanation: From the first term we can take 2[tex]x^{5\\}[/tex] and an x is the rest. From the second term we take 2[tex]x^{5\\}[/tex] either, but here the rest is 14. That's the reason the common factor is 2[tex]x^{5\\}[/tex].