Question 4*+If \(\lim_{x\to1^-}f(x)=3\) and \(\lim_{x\to1^+}f(x)=7\), does \(\lim_{x\to1}f(x)\) exist?
Question 11***+For \(f(x)=\begin{cases}x+1,&x<0\2x+1,&x>0\end{cases}\), find \(\lim_{x\to0^-}f(x)\), \(\lim_{x\to0^+}f(x)\), and the two-sided limit.
Question 12***+For \(f(x)=\begin{cases}1,&x<3\4,&x>3\end{cases}\), determine whether \(\lim_{x\to3}f(x)\) exists.
Question 14****Evaluate \(\lim_{x\to\infty}\frac{7x-1}{x^2+4}\) and interpret the horizontal behavior.
Question 18*****A student says \(\lim_{x\to\infty}\frac{3x^2+10}{x}=3\) by comparing coefficients. Diagnose the error and find the correct behavior.
Question 19*****Construct a simple piecewise function whose left-hand limit at \(0\) is \(-1\) and right-hand limit at \(0\) is \(1\), and state the two-sided limit.
Question 20*****Explain why \(\lim_{x\to a}f(x)=+\infty\) is not a finite limit, even though it describes limiting behavior.