The function $$f(x) = \begin{cases} x^3 + ax & (x < 1) \\ bx^2 + x + 1 & (x \geq 1) \end{cases}$$ is differentiable at $x = 1$. What is the value of $a + b$? (Here, $a, b$ are constants.) [4 points] (1) 5 (2) 6 (3) 7 (4) 8 (5) 9
The function
$$f(x) = \begin{cases} x^3 + ax & (x < 1) \\ bx^2 + x + 1 & (x \geq 1) \end{cases}$$
is differentiable at $x = 1$. What is the value of $a + b$?\\
(Here, $a, b$ are constants.) [4 points]\\
(1) 5\\
(2) 6\\
(3) 7\\
(4) 8\\
(5) 9