For problem 8, the function is expressed as $f(x)=\sqrt{3x+25}$, and its derivative is calculated using the chain rule. In problem 9, the slope of the tangent line is confirmed to be 8, but the function value at $f(-1)$ is incorrectly stated; it should be $-4(-1)^2$. For problem 10, the derivative is correctly identified as -2x + 5, but the slope of the tangent line at x=2 is not provided, which is simply the derivative evaluated at that point. Understanding the relationship between derivatives and the slopes of tangent lines is crucial for solving these calculus problems effectively.