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Which statement best describes the limit shown below?

lim_(x rarr oo)(-7x^(70))/(3x^(9)+10e^(x))
The limit equals zero
The limit does not exist
The limit exists and does not equal zero

Which statement best describes the limit shown below?\newlinelimx7x703x9+10ex \lim _{x \rightarrow \infty} \frac{-7 x^{70}}{3 x^{9}+10 e^{x}} \newlineThe limit equals zero\newlineThe limit does not exist\newlineThe limit exists and does not equal zero

Full solution

Q. Which statement best describes the limit shown below?\newlinelimx7x703x9+10ex \lim _{x \rightarrow \infty} \frac{-7 x^{70}}{3 x^{9}+10 e^{x}} \newlineThe limit equals zero\newlineThe limit does not exist\newlineThe limit exists and does not equal zero
  1. Given Limit Expression: We are given the limit expression limx(7x703x9+10ex)\lim_{x \to \infty}\left(\frac{-7x^{70}}{3x^{9}+10e^{x}}\right). To find the behavior of this limit as xx approaches infinity, we need to analyze the degrees of the polynomials in the numerator and the denominator, as well as the exponential function in the denominator.
  2. Degree Analysis: First, let's consider the highest power of xx in both the numerator and the denominator. In the numerator, the highest power of xx is x70x^{70}, and in the denominator, the highest power of xx is x9x^{9}. The exponential function exe^{x} grows faster than any polynomial, but we will first compare the polynomial terms.
  3. Dominant Term Comparison: Since the degree of xx in the numerator (7070) is much higher than the degree of xx in the denominator (99), the polynomial part of the fraction will dominate the behavior of the limit as xx approaches infinity. The exponential term 10ex10e^{x} becomes insignificant compared to the x70x^{70} term as xx grows larger.
  4. Simplification by Division: As xx approaches infinity, the fraction (7x70)/(3x9)(-7x^{70})/(3x^{9}) will dominate the behavior of the limit. We can simplify this fraction by dividing both the numerator and the denominator by x9x^{9}, the highest power of xx in the denominator.
  5. Exponential Term Behavior: After dividing by x9x^{9}, we get (7x61)/(3+10ex/x9)(-7x^{61})/(3+10e^{x}/x^{9}). As xx approaches infinity, the term 10ex/x910e^{x}/x^{9} goes to zero because the exponential function exe^{x} grows slower than x9x^{9}. Therefore, the denominator approaches 33.
  6. Final Simplified Expression: Now, we are left with the simplified expression (7x61)/3(-7x^{61})/3. As xx approaches infinity, x61x^{61} also approaches infinity, and thus the whole expression approaches negative infinity.
  7. Limit Evaluation: Since the expression approaches negative infinity, the limit does not equal 00, and it does exist. Therefore, the correct statement is "The limit exists and does not equal 00."

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