Question 7ba3505c

The function $f$ is defined by $f\left(x\right)=a\sqrt{x+b}$, where $a$ and $b$ are constants. In the xy-plane, the graph of $y=f\left(x\right)$ passes through the point $\left(-24,0\right)$, and $f\left(24\right)<0$. Which of the following must be true?