Answer:
• From common difference of an arithmetic progression:
[tex]{ \tt{u _{3} - u _{2} = u _{2} - u _{1} }}[/tex]
• substitute into the expression above:
[tex]{ \tt{ \{(6k - 2) - (4k + 1) \}} = \{(4k + 1) - (3k - 1) \}} \\ \\ { \tt{6k - 4k - 2 - 1 = 4k - 3k + 1 + 1}} \\ \\ { \tt{2k - 3 = k + 2}} \\ \\ { \tt{2k - k = 2 + 3}} \\ \\ { \underline{ \underline{ \bf{ \: \: k = 5 \: \: }}}}[/tex]
