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8.01 Limits

Worksheet
Limits
1

Use limit notation to describe the following sentence:

The value that the function y = x + 4 approaches as x approaches 168.

2

Consider the function f \left( x \right) = 5 x^{2} + 1.

a

Complete the table to find the exact values of f \left( x \right) as x gets closer and closer to 2 from the left, and closer and closer to 2 from the right:

x1.91.991.9992.0012.012.1
f(x)
b

Hence, find the value of \lim_{x \to 2}\left( 5 x^{2} + 1\right).

3

Consider the function f \left( x \right) = \dfrac{2 - x}{x^{2} + 2}.

a

Complete the table to find the values of f \left( x \right) as x gets closer and closer to 0 from the left, and closer and closer to 0 from the right. Give your answers correct to four decimal places.

x-0.1-0.01-0.0010.0010.010.1
f(x)
b

Hence, find the value of \lim_{x \to 0}\left(\dfrac{2 - x}{x^{2} + 2}\right).

4

Consider the function f \left( x \right) = \dfrac{x^{2} - 4 x}{x - 4}.

a

Complete the table to find the values of f \left( x \right) as x gets closer and closer to 4 from the left, and closer and closer to 4 from the right:

x3.93.993.9994.0014.014.1
f(x)
b

Hence, find the value of \lim_{x \to 4}\left(\dfrac{x^{2} - 4 x}{x - 4}\right).

5

Consider \lim_{x \to - 5 }\left(\dfrac{x^{2} + 4}{x + 5}\right).

a

Complete the table to find the values of f \left( x \right) as x gets closer and closer to 5 from the left, and closer and closer to 5 from the right:

x-5.1-5.01-5.001-4.999-4.99-4.9
\dfrac{x^2+4}{x+5}
b

Does the above limit exist?

6

The graph of the function \dfrac{x^{2} - 1}{x + 1} is shown below:

a

If we start at x = - 3 and move along the function to the right towards x = -1, what y-value do we approach?

b

If we start at x = 1 and move along the function to the left towards x = -1, what y-value do we approach?

c

Hence, write a sentence to describe the limiting behaviour of \dfrac{x^{2} - 1}{x + 1} at x=-1.

d

Write this same sentence as an equation, using limit notation.

-5
-4
-3
-2
-1
1
2
3
4
5
x
-5
-4
-3
-2
-1
1
2
3
4
5
y
7

Consider the graph of a function, f \left( x \right):

Does \lim_{x \to 3} f \left( x \right) exist? If yes, state the value of the limit.

1
2
3
4
5
x
-2
-1
1
2
3
4
y
8

Consider the graph of a function, f \left( x \right):

Does \lim_{x \to 2} f \left( x \right) exist? If yes, state the value of the limit.

-2
-1
1
2
3
4
5
x
-2
-1
1
2
3
4
y
9

Consider the graph of a function, f \left( x \right):

Does \lim_{x \to 3} f \left( x \right) exist? If yes, state the value of the limit.

-1
1
2
3
4
5
x
-2
-1
1
2
3
4
y
10

Evaluate:

a
\lim_{x \to 5} 9
b

\lim_{x \to 3}\left( - 2 \right)

c

\lim_{x \to 6}\left( 5 x\right)

d

\lim_{x \to 6}\left( 4 x^{2}\right)

e

\lim_{x \to 5} \sqrt{41 - x}

f

\lim_{x \to 1}\left( 3 x^{4} - 5 x^{3} + 2\right)

g

\lim_{x \to - 4 }\left(\dfrac{x^{2} + 6 x + 8}{x + 4}\right)

h

\lim_{x \to 3}\left(\dfrac{x^{2} - 9 x + 18}{x - 3}\right)

i

\lim_{x \to 0}\left(\dfrac{x^{2} - 4 x}{x}\right)

j

\lim_{x \to - 3 }\left(\dfrac{5 x + 3}{3 x + 4}\right)

k

\lim_{x \to - 5 }\left(\dfrac{x^{2} - 25}{x + 5}\right)

l

\lim_{x \to - 3 }\left(\dfrac{x^{2} + 3 x}{x^{2} - 9}\right)

m

\lim_{x \to 3}\left(\dfrac{x^{2} - 5 x + 6}{x - 3}\right)

n

\lim_{x \to - 5 }\left(\dfrac{x^{2} + x - 20}{x^{2} - 25}\right)

o

\lim_{x \to - 5 }\left(\dfrac{\left(x + 5\right)^{2}}{x^{2} + 2 x - 15}\right)

p

\lim_{x \to 0}\left(\dfrac{x^{2} - 36}{x^{2} + 36}\right)

q

\lim_{x \to 3}\left(\dfrac{x^{3} - 27}{x^{4} - 81}\right)

r

\lim_{x \to 4}\left(\dfrac{x - 4}{\sqrt{x} - 2}\right)

s

\lim_{x \to 5}\left(\dfrac{\dfrac{1}{x} - \dfrac{1}{5}}{x - 5}\right)

t

\lim_{x \to - 9 }\left(\dfrac{x^{3} + 18 x^{2} + 81 x}{x^{2} + 5 x - 36}\right)

u

\lim_{x \to 3}\left(\dfrac{\left(x - 3\right)^{2}}{3 x^{2} - 13 x + 12}\right)

11

Consider the function f \left( x \right) = \dfrac{x^{2} + 7 x + 10}{x + 5}.

a

Evaluate \dfrac{x^{2} + 7 x + 10}{x + 5} at x = - 5.

b

Evaluate \lim_{x \to - 5 }\left(\dfrac{x^{2} + 7 x + 10}{x + 5}\right).

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