\[ f(x)=3 x^{3}+5 x^{2}+7 x+4 \] Step 3 of 3 : Find $f(a+1)$. Answer \[ f(a+1)= \]

Step 1 ：\(f(a+1) = 3(a+1)^3 + 5(a+1)^2 + 7(a+1) + 4\)

Step 2 ：\(f(a+1) = 3(a^3 + 3a^2 + 3a + 1) + 5(a^2 + 2a + 1) + 7(a + 1) + 4\)

Step 3 ：\(f(a+1) = 3a^3 + 9a^2 + 9a + 3 + 5a^2 + 10a + 5 + 7a + 7 + 4\)

Step 4 ：\(f(a+1) = 3a^3 + 14a^2 + 26a + 19\)

Step 5 ：\(\boxed{f(a+1) = 3a^3 + 14a^2 + 26a + 19}\)