(3x-4y)^2 = (3x-4y)(3x-4y)= 3x(3x-4y) - 4y(3x-4y)= 9x^2 - 12xy - 12xy + 16y^2= 9x^2 - 24xy + 16y^2
(m-6)(m+6) = m^2 - 6m + 6m - 36= m^2 - 36
(3x-4y)^2 = (3x-4y)(3x-4y)
= 3x(3x-4y) - 4y(3x-4y)
= 9x^2 - 12xy - 12xy + 16y^2
= 9x^2 - 24xy + 16y^2
(m-6)(m+6) = m^2 - 6m + 6m - 36
= m^2 - 36