This equation can be rewritten as:
[tex]6d^{2} + 14d + 3d + 7[/tex]
Factor out a common 2d from the first two terms:
[tex]2d(3d+7) + 3d + 7[/tex]
Factor out a 1 from the last two terms:
[tex]2d(3d+7) + 1(3d+7)[/tex]
Now regroup the terms into the fully factored equation:
[tex](2d+1)(3d+7)[/tex]