Understanding Growth at Infinity

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Alva Benedict B., PhD
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Alva Benedict B. is an experienced mathematician and math content developer with over 15 years of teaching and tutoring experience across high school, undergraduate, and test prep levels. He specializes in Algebra, Calculus, and Statistics, and holds advanced academic training in Mathematics with extensive expertise in LaTeX-based math content development.
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| Questions: 15 | Updated: Feb 6, 2026
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1) What is the limit as x→∞ of (5x³ + 2x)/(2x³ + 7)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, both the numerator and denominator are polynomials of degree 2. When the degrees are equal, the limit is the ratio of the leading coefficients. The leading coefficient of the numerator is 3, and the leading coefficient of the denominator is 2. Therefore, the limit is 3/2.

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About This Quiz
Understanding Growth At Infinity - Quiz

Ready to dive deeper into end behavior? This quiz helps you sharpen your skills by working with higher powers, square roots, and rational expressions with matching or mismatched degrees. You’ll explore when a limit approaches a constant, when it becomes zero, and when a function heads toward infinity. By comparing... see morehow functions grow and recognizing patterns in formulas, you’ll strengthen your understanding of limits and horizontal asymptotes.
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2) What is the limit as x→∞ of (3x + 4)/(x² + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, the numerator is a polynomial of degree 1, and the denominator is a polynomial of degree 2. When the degree of the numerator is less than the degree of the denominator, the limit is 0. This is because the denominator grows much faster than the numerator as x approaches infinity, making the fraction approach 0.

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3) What is the limit as x→∞ of (x² + 3x + 2)/(4x² + 5)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, both the numerator and denominator are polynomials of degree 3. When the degrees are equal, the limit is the ratio of the leading coefficients. The leading coefficient of the numerator is 1, and the leading coefficient of the denominator is 4. Therefore, the limit is 1/4.

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4) What is the limit as x→∞ of (2x^4 + 3x²)/(x^4 + 5x³ + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, the numerator is a polynomial of degree 2, and the denominator is a polynomial of degree 3. When the degree of the numerator is less than the degree of the denominator, the limit is 0. This is because the denominator grows much faster than the numerator as x approaches infinity, making the fraction approach 0.

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5) What is the limit as x→∞ of (x³ + 2)/(2x² + 3)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, both the numerator and denominator are polynomials of degree 1. When the degrees are equal, the limit is the ratio of the leading coefficients. The leading coefficient of the numerator is 3, and the leading coefficient of the denominator is 2. Therefore, the limit is 3/2.

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6) What is the limit as x→∞ of √(4x² + 1)/x?

Explanation

To Find the limit as x→∞ of √(x² + 4)/x, we factor out x² from inside the square root: √(x²(1 + 4/x²))/x. Recall that √(x²) = |x|. Since x approaches positive infinity, |x| = x. The expression simplifies to x√(1 + 4/x²)/x, which reduces to √(1 + 4/x²). As x approaches infinity, 4/x² approaches 0, so the limit is 1.

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7) What is the limit as x→∞ of (x² + 4)/(x + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, the numerator is a polynomial of degree 2, and the denominator is a polynomial of degree 1. When the degree of the numerator is greater than the degree of the denominator, the limit is infinity (or negative infinity, depending on the signs of the leading coefficients). In this case, both leading coefficients are positive, so the limit is infinity.

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8) What is the limit as x→∞ of (3x^4 + 2x³)/(5x^4 + x² + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, both the numerator and denominator are polynomials of degree 3. When the degrees are equal, the limit is the ratio of the leading coefficients. The leading coefficient of the numerator is 2, and the leading coefficient of the denominator is 3. Therefore, the limit is 2/3.

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9) What is the limit as x→∞ of (2x + 5)/(x² + 3x + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, the numerator is a polynomial of degree 1, and the denominator is a polynomial of degree 2. When the degree of the numerator is less than the degree of the denominator, the limit is 0. This is because the denominator grows much faster than the numerator as x approaches infinity, making the fraction approach 0.

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10) What is the limit as x→∞ of (4x³ + 2x)/(2x³ + 5x² + 1)?

Explanation

To Find the limit as x→∞ of a rational function, we compare the degrees of the numerator and denominator. Here, both the numerator and denominator are polynomials of degree 2. When the degrees are equal, the limit is the ratio of the leading coefficients. The leading coefficient of the numerator is 4, and the leading coefficient of the denominator is 2. Therefore, the limit is 4/2 = 2.

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11) What does the limit as x approaches infinity of f(x) = 5 tell us about the function f(x)?

Explanation

When the limit as x approaches infinity of a function f(x) equals a finite number L, it means that as x gets larger and larger, the values of f(x) get closer and closer to L. Graphically, this means that the graph of f(x) approaches the horizontal line y = L as x moves to the right. This line y = L is called a horizontal asymptote of the function.

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12) Evaluate limx→∞ (8x⁷ - 3x⁴ + 9)/( -2x⁷ + 5x⁶ - 1)

Explanation

For rational functions (polynomials divided by polynomials), the limit as x approaches infinity depends on the degrees of the numerator and denominator. If the degree of the numerator is less than the degree of the denominator, the limit is 0. If the degree of the numerator equals the degree of the denominator, the limit is the ratio of the leading coefficients. If the degree of the numerator is greater than the degree of the denominator, the limit is infinity or negative infinity. Additionally, limits at infinity exist for many types of functions, not just polynomials.

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13) What does the limit as x approaches infinity of f(x) = -∞ tell us about the function f(x)?

Explanation

When the limit as x approaches infinity of a function f(x) equals infinity, it means that as x gets larger and larger, the values of f(x) also get larger and larger without any upper bound. In other words, the function grows without bound as x increases. This is different from having a horizontal asymptote, which would occur if the limit was a finite number. It's also different from having a vertical asymptote, which relates to the behavior of the function as x approaches a finite value, not infinity.

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14) If the limit as x approaches infinity of f(x)/g(x) = infinity, what can we conclude about the relative growth rates of f(x) and g(x)?

Explanation

If the limit as x approaches infinity of f(x)/g(x) = 0, it means that as x gets larger and larger, the value of f(x) becomes negligible compared to g(x). In other words, g(x) grows much faster than f(x). This is why their ratio approaches 0. If f(x) grew faster than g(x), the ratio would approach infinity. If they grew at the same rate, the ratio would approach a non-zero constant.

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15) Which of the following functions has a horizontal asymptote at y = 2?

Explanation

A function has a horizontal asymptote if the limit as x approaches infinity (or negative infinity) is a finite number. For option A, f(x) = x² + 3x + 2, the limit as x approaches infinity is infinity, so there is no horizontal asymptote. For option B, f(x) = 2^x, the limit as x approaches infinity is also infinity, so there is no horizontal asymptote. For option C, f(x) = (3x² + 1)/(x² + 4), the limit as x approaches infinity is 3 (the ratio of the leading coefficients), so there is a horizontal asymptote at y = 3. For option D, f(x) = ln(x), the limit as x approaches infinity is infinity, so there is no horizontal asymptote.

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Alva Benedict B. |PhD
College Expert
Alva Benedict B. is an experienced mathematician and math content developer with over 15 years of teaching and tutoring experience across high school, undergraduate, and test prep levels. He specializes in Algebra, Calculus, and Statistics, and holds advanced academic training in Mathematics with extensive expertise in LaTeX-based math content development.
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What is the limit as x→∞ of (5x³ + 2x)/(2x³ + 7)?
What is the limit as x→∞ of (3x + 4)/(x² + 1)?
What is the limit as x→∞ of (x² + 3x + 2)/(4x² + 5)?
What is the limit as x→∞ of (2x^4 + 3x²)/(x^4 + 5x³ + 1)?
What is the limit as x→∞ of (x³ + 2)/(2x² + 3)?
What is the limit as x→∞ of √(4x² + 1)/x?
What is the limit as x→∞ of (x² + 4)/(x + 1)?
What is the limit as x→∞ of (3x^4 + 2x³)/(5x^4 + x² + 1)?
What is the limit as x→∞ of (2x + 5)/(x² + 3x + 1)?
What is the limit as x→∞ of (4x³ + 2x)/(2x³ + 5x² + 1)?
What does the limit as x approaches infinity of f(x) = 5 tell us about...
Evaluate limx→∞ (8x⁷ - 3x⁴ + 9)/( -2x⁷ + 5x⁶ - 1)
What does the limit as x approaches infinity of f(x) = -∞ tell us...
If the limit as x approaches infinity of f(x)/g(x) = infinity, what...
Which of the following functions has a horizontal asymptote at y = 2?
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