Which statement best describes the limit shown below?x→∞lim3x9+10ex−7x70The limit equals zeroThe limit does not existThe limit exists and does not equal zero
Q. Which statement best describes the limit shown below?x→∞lim3x9+10ex−7x70The limit equals zeroThe limit does not existThe limit exists and does not equal zero
Given Limit Expression: We are given the limit expression limx→∞(3x9+10ex−7x70). To find the behavior of this limit as x 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.
Degree Analysis: First, let's consider the highest power of x in both the numerator and the denominator. In the numerator, the highest power of x is x70, and in the denominator, the highest power of x is x9. The exponential function ex grows faster than any polynomial, but we will first compare the polynomial terms.
Dominant Term Comparison: Since the degree of x in the numerator (70) is much higher than the degree of x in the denominator (9), the polynomial part of the fraction will dominate the behavior of the limit as x approaches infinity. The exponential term 10ex becomes insignificant compared to the x70 term as x grows larger.
Simplification by Division: As x approaches infinity, the fraction (−7x70)/(3x9) will dominate the behavior of the limit. We can simplify this fraction by dividing both the numerator and the denominator by x9, the highest power of x in the denominator.
Exponential Term Behavior: After dividing by x9, we get (−7x61)/(3+10ex/x9). As x approaches infinity, the term 10ex/x9 goes to zero because the exponential function ex grows slower than x9. Therefore, the denominator approaches 3.
Final Simplified Expression: Now, we are left with the simplified expression (−7x61)/3. As x approaches infinity, x61 also approaches infinity, and thus the whole expression approaches negative infinity.
Limit Evaluation: Since the expression approaches negative infinity, the limit does not equal 0, and it does exist. Therefore, the correct statement is "The limit exists and does not equal 0."