Answer:
4x² -29x +51
Explanation:
Put x-3 where x is in the original function definition, then "simplify". I think you'll find it convenient to rewrite the original function definition first.
... g(x) = 4x² -5x = x(4x -5)
Substituting, we have
... g(x-3) = (x -3)(4(x -3) -5)
... = (x -3)(4x -17) . . . . . simplify right factor
... = 4x² -12x -17x +51
... g(x -3) = 4x² -29x +51