You basically do (6a + b)(6a + b) [Multiply them out].
6a(6a + b) + b(6a + b)
36 a^2 + 6ab + 6ab + b^2
36a^2 + 12ab + b^2.
You basically do (6a + b)(6a + b) [Multiply them out].
6a(6a + b) + b(6a + b)
36 a^2 + 6ab + 6ab + b^2
36a^2 + 12ab + b^2.