Answer:
[tex]x {}^{2} \times + 4x[/tex]
Step-by-step explanation:
[tex]f(x + 4) = (x + 4) {}^{2} - 3(x + 4) - 4 \\ = x {}^{2} + 8x + 16 - 3x - 12 - 4 \\ = x {}^{2} + 4x[/tex]