To evaluate the limit \(\lim _{x \rightarrow 0} \frac{x^{100}+7 x^{2}}{x^{50}-4 x^{2}}\), we need to analyze the behavior of the numerator and the denominator as \(x\) approaches 0. We can simplify the expression by factoring out the lowest power of \(x\) in both the numerator and the denominator.
Step 1: Define the Limit Expression
We need to evaluate the limit:
\[
\lim _{x \rightarrow 0} \frac{x^{100} + 7x^2}{x^{50} - 4x^2}
\]
Step 2: Simplify the Expression
To simplify the expression, we factor out the lowest power of \(x\) in both the numerator and the denominator. The lowest power in the numerator is \(x^2\) and in the denominator is also \(x^2\):
\[
\frac{x^{100} + 7x^2}{x^{50} - 4x^2} = \frac{x^2(x^{98} + 7)}{x^2(x^{48} - 4)}
\]
Step 3: Cancel Common Factors
We can cancel the common factor \(x^2\) from the numerator and the denominator:
\[
\frac{x^{98} + 7}{x^{48} - 4}
\]
Step 4: Evaluate the Limit
Now, we evaluate the limit as \(x\) approaches 0:
\[
\lim _{x \rightarrow 0} \frac{x^{98} + 7}{x^{48} - 4}
\]
As \(x \rightarrow 0\), \(x^{98} \rightarrow 0\) and \(x^{48} \rightarrow 0\). Therefore, the expression simplifies to:
\[
\frac{0 + 7}{0 - 4} = \frac{7}{-4} = -\frac{7}{4}
\]