Understanding Infinite Limits and Unbounded Function Behavior

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| Questions: 15 | Updated: Dec 17, 2025
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1) Evaluate lim_{x→4⁻} 7/(4-x)

Explanation

As x approaches 4 from the left (x→4⁻), the expression (4-x) approaches 0 from the positive side because x is less than 4. When we divide 7 by a very small positive number, the result becomes very large and positive.

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About This Quiz
Understanding Infinite Limits And Unbounded Function Behavior - Quiz

How do different powers in the denominator change infinite limit behavior? This quiz has you work with expressions like 1/(x − a), 1/(x − a)², 1/(x − a)³, and similar forms involving constants and shifts. You’ll practice evaluating one-sided infinite limits, deciding whether the function goes to +∞ or −∞,... see moreand matching that to the sign of the denominator near the critical point. You’ll also distinguish between holes and vertical asymptotes and count how many asymptotes a function has by factoring its denominator. It’s a solid step toward fluency with vertical asymptotes and unbounded behavior.
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2) Evaluate lim_{x→-2⁺} 1/(x+2)³

Explanation

As x approaches -2 from the right (x→-2⁺), x is greater than -2, so (x+2) is positive and approaches 0. When we cube a positive number, the result is positive. When we divide 1 by a very small positive number cubed, the result becomes very large and positive.

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3) Which function has a vertical asymptote at x = -2?

Explanation

A vertical asymptote occurs where the denominator equals zero and the numerator is not zero at that point. For f(x) = (x-2)/(x+2), the denominator equals zero when x = -2, and the numerator equals -4 at x = -2, which is not zero. Therefore, there is a vertical asymptote at x = -2.

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4) Evaluate limx→0⁻ 1/x³

Explanation

As x approaches 0 from the left (x→0⁻), x³ approaches 0 from the negative side because cubing a negative number gives a negative result. When we divide 1 by a very small negative number, the result becomes very large and negative.

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5) For the function f(x) = 2/(x²-9), what happens as x approaches 3 from the left?

Explanation

As x approaches 3 from the left (x→3⁻), x is less than 3, so (x²-9) approaches 0 from the negative side because (3)²-9 = 0 and for x slightly less than 3, x² is slightly less than 9. When we divide 2 by a very small negative number, the result becomes very large and negative.

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6) Evaluate limx→π/2⁺ 1/(x-π/2)

Explanation

As x approaches π/2 from the right (x→π/2⁺), the denominator (x-π/2) approaches 0 from the positive side. When we have 1 divided by a very small positive number, the result becomes very large and positive.

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7) What is the difference between a vertical asymptote and a hole in the graph?

Explanation

A vertical asymptote represents behavior where the function grows without bound as x approaches a certain value. A hole occurs when there is a factor that cancels in the numerator and denominator, resulting in a point where the function is undefined but the limit exists and is finite.

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8) Evaluate lim_{x→-3⁺} 4/(x+3)²

Explanation

As x approaches -3 from the right (x→-3⁺), the denominator (x+3)² approaches 0 from the positive side (since squaring always gives a positive result). When we divide 4 by a very small positive number, the result becomes very large and positive.

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9) For f(x) = 1/(5-x), what is lim_{x→5⁻} f(x)?

Explanation

As x approaches 5 from the left (x→5⁻), x is less than 5, so (5-x) is positive and approaches 0. When we divide 1 by a very small positive number, the result becomes very large and positive.

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10) Which expression would produce a vertical asymptote at x = 2?

Explanation

For a vertical asymptote at x = 2, we need the function to be undefined at x = 2 and approach infinity as x approaches 2. The expression 1/(x-2) satisfies this: it is undefined at x = 2 and approaches positive or negative infinity as x approaches 2 from either side.

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11) Evaluate lim_{x→6⁺} -2/(x-6)

Explanation

As x approaches 6 from the right (x→6⁺), the denominator (x-6) approaches 0 from the positive side. When we have -2 divided by a very small positive number, the result becomes very large and negative.

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12) When we say lim_{x→a} f(x) = ∞, what does this mean?

Explanation

When we write lim_{x→a} f(x) = ∞, we mean that as x gets arbitrarily close to a, the values of f(x) become arbitrarily large. This describes unbounded behavior, not that the function actually equals infinity (which is not a number).

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13) Evaluate lim_{x→1⁻} 3/(1-x)²

Explanation

As x approaches 1 from the left (x→1⁻), the denominator (1-x)² approaches 0 from the positive side (since squaring always gives a positive result). When we divide 3 by a very small positive number, the result becomes very large and positive.

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14) How many vertical asymptotes does f(x) = 1/(x²-4x+3) have?

Explanation

To find vertical asymptotes, we set the denominator equal to zero: x²-4x+3 = 0. Factoring gives (x-1)(x-3) = 0, so x = 1 or x = 3. Both values make the denominator zero while the numerator remains 1, creating two vertical asymptotes.

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15) Evaluate lim_{x→0⁺} -1/x

Explanation

As x approaches 0 from the right (x→0⁺), the denominator x approaches 0 from the positive side. When we have -1 divided by a very small positive number, the result becomes very large and negative.

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Evaluate lim_{x→4⁻} 7/(4-x)
Evaluate lim_{x→-2⁺} 1/(x+2)³
Which function has a vertical asymptote at x = -2?
Evaluate limx→0⁻ 1/x³
For the function f(x) = 2/(x²-9), what happens as x approaches 3 from...
Evaluate limx→π/2⁺ 1/(x-π/2)
What is the difference between a vertical asymptote and a hole in the...
Evaluate lim_{x→-3⁺} 4/(x+3)²
For f(x) = 1/(5-x), what is lim_{x→5⁻} f(x)?
Which expression would produce a vertical asymptote at x = 2?
Evaluate lim_{x→6⁺} -2/(x-6)
When we say lim_{x→a} f(x) = ∞, what does this mean?
Evaluate lim_{x→1⁻} 3/(1-x)²
How many vertical asymptotes does f(x) = 1/(x²-4x+3) have?
Evaluate lim_{x→0⁺} -1/x
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