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AP Calculus AB
Unit 1: Limits and Continuity
1.13 Removing Discontinuities
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Cards (49)
In a jump discontinuity, the function approaches different limits from the
left
and right at a specific point.
Give an example of a function with a removable discontinuity.
f(x) = \frac{x^2 - 4}{x - 2}</latex>
Steps to remove a removable discontinuity:
1️⃣ Factor the numerator and denominator
2️⃣ Simplify the expression
3️⃣ Check the limit as x approaches the discontinuity
4️⃣ Replace the discontinuous function with a continuous equivalent
A removable discontinuity occurs when the function has a
hole
or
jump
at a point, but the
limit
exists.
By canceling common factors, removable
discontinuities
can be eliminated.
True
A removable discontinuity occurs when the function has a hole or
jump
What is the first step when removing a removable discontinuity by factoring the numerator and denominator?
Factor both numerator and denominator
When simplifying
\frac{x^{2} - 9}{x^{2} +
6
x
+
6x +
6
x
+
9}
, the denominator factors to (x + 3)(x + 3)
The limit of
x
2
−
9
x
−
3
\frac{x^{2} - 9}{x - 3}
x
−
3
x
2
−
9
as
x
x
x
approaches 3 is 6
What is the domain restriction needed for the function
f
(
x
)
=
f(x) =
f
(
x
)
=
1
x
\frac{1}{x}
x
1
?
x
≠
0
x \neq 0
x
=
0
What feature of a function indicates an infinite discontinuity?
Vertical asymptote
Match the type of discontinuity with its definition:
Removable ↔️ Limit exists at the point
Jump ↔️ Sudden change in value
Infinite ↔️ Vertical asymptote
Factoring the numerator and denominator is essential for removing
removable
discontinuities.
What is the simplified form of \( f(x) = \frac{x^2 - 9}{x - 3} \) after canceling common factors?
x + 3
The left-hand and right-hand limits must be equal for a limit to exist at a discontinuity.
True
Steps to replace a discontinuous function with a continuous equivalent:
1️⃣ Identify the discontinuity
2️⃣ Calculate the limit
3️⃣ Redefine the function
Discontinuities occur in functions where the graph breaks or skips a
point
An infinite discontinuity occurs when the function approaches infinity as it nears a specific point.
True
The function
f
(
x
)
=
f(x) =
f
(
x
)
=
1
/
x
1 / x
1/
x
has an infinite discontinuity at
x
=
x =
x
=
0
0
0
.
True
How is an infinite discontinuity removed?
Restrict the domain
What is the example function given for an infinite discontinuity?
f
(
x
)
=
f(x) =
f
(
x
)
=
1
x
\frac{1}{x}
x
1
What is the simplified form of the function
f
(
x
)
=
f(x) =
f
(
x
)
=
x
2
−
9
x
−
3
\frac{x^{2} - 9}{x - 3}
x
−
3
x
2
−
9
after removing the discontinuity?
f
(
x
)
=
f(x) =
f
(
x
)
=
x
+
x +
x
+
3
3
3
A jump discontinuity exists when the limit exists at the point of discontinuity.
False
Steps to remove a removable discontinuity by factoring the numerator and denominator:
1️⃣ Factor both the numerator and denominator
2️⃣ Cancel common factors
3️⃣ Redefine the function at the point of discontinuity
Why is it important to check the limit as x</latex> approaches a discontinuity?
To determine if it is removable
A jump discontinuity can be removed by redefining the function at the point of discontinuity.
False
What type of discontinuity occurs when a function has a hole at a point but the limit exists?
Removable
Identifying and removing discontinuities is a crucial step in analyzing the behavior of a function.
True
What is an example of a function with an infinite discontinuity?
f(x) = 1/x
What is one benefit of factoring when dealing with discontinuities?
Simplifies complex expressions
To simplify an expression, identify common factors and
cancel
them.
What is the limit of \( \frac{x^2 - 4}{x - 2} \) as \( x \to 2 \)?
4
What is the limit of \( \frac{x^2 - 9}{x - 3} \) as \( x \to 3 \)?
6
What is a removable discontinuity characterized by?
Limit exists but not function value
Match the type of discontinuity with its characteristic:
Removable ↔️ Limit exists but doesn't match function value
Jump ↔️ Different left and right limits
Infinite ↔️ Function approaches infinity
Discontinuities are points where a function is not
continuous
.
Identifying and removing discontinuities is essential for analyzing the behavior of a function.
True
Steps to remove a removable discontinuity by factoring:
1️⃣ Original function
2️⃣ Factor the numerator
3️⃣ Cancel common factors
4️⃣ Simplify the function
How many main types of discontinuities are there in a function?
Three
Match the type of discontinuity with its example:
Removable ↔️
f
(
x
)
=
f(x) =
f
(
x
)
=
x
2
−
4
x
−
2
\frac{x^{2} - 4}{x - 2}
x
−
2
x
2
−
4
Jump ↔️
f
(
x
)
=
f(x) =
f
(
x
)
=
\begin{cases} x & \text{if } x < 0 \\ x +
1 & \text{if } x \geq 0 \end{cases}
Infinite ↔️
f
(
x
)
=
f(x) =
f
(
x
)
=
1
x
\frac{1}{x}
x
1
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