CALCULUS
CH 1 NOTES
Learning Target: The students will be able to find the limit of a function numerically using tables
1.2
and graphically. The students will also be able to identify the 3 cases in which a limit does not exist.
Definition: If a function gets closer and closer to a number as x approaches from either side, then that
number is called the limit of the function f(x) as x approaches it.
lim f ( x)  L
x c
We find the limits 3 ways:
1. Numerically (table, substitution)
2. graphically
3. analytically (use algebra to manipulate the function)
Find the following limits numerically (by table)
EX:
lim
x 5
4 x 3
x5
x
f(x)
EX:
-5.1
x3  8
x 2 x  2
lim
x
3.9
-5.01
3.99
-5.001
3.999
-4.999
4.001
-4.99
4.01
-4.9
4.1
How do you derive the table???
EX:
x
4

lim x  1 5
x 4
x4
x
OVER
f(x)
f(x)
Find the limit graphically.
 x3  3 x  1
lim f ( x) if f ( x)  

x 1
x  1
2
EX:
EX:
Find
a. f(1)
b.
lim f ( x )
c.
f(4)
d.
lim f ( x )
x 1
x4
There are 3 cases where the limit does not exist.
1. f(x) approaches different numbers from each side of c.
EX:
2.
x 0
x
x
f(x) goes to infinity at c (i.e. a vertical asymptote)
EX:
3.
lim
1
x0 x
lim
f(x) oscillates between two numbers as it approaches c
EX:
1
lim(sin )
x 0
x
1.3
Learning Target:
substitution.
The student will be able to find the limit using the numerical method of
Remember, there are three ways to find the limit:
1. Numerically
2. graphically
3. analytically
Find the limit by direct substitution:
EX:
EX:
lim (3 x  2)
Given
a.
EX:
EX:
b.
lim f ( x )
x4
x2
x4
lim f ( x) 
x c
lim 4 f ( x) b.
x c
lim g ( x)
c.
lim g ( f ( x))
c.
d.
lim[
x  21
x4
3
1
and lim g ( x) 
x

c
2
2
lim[ f ( x)  g ( x)]
x c
lim[ f ( x) g ( x)]
x c
EX:
lim tan x
x 
given
x 2
f ( x)  2 x 2  3x  1 and g ( x)  3 x  6
Given
a.
EX:
EX:
x 3
lim
lim cos x
x
f ( x)  x  7 and g ( x)  x 2
find
5
3
lim g ( f ( x))
x 3
x c
f ( x)
]
g ( x)
1.3 con’t
Learning Target: The student will find limits analytically and will learn and practice the 2
special trig limits.
EX: Write a function that agrees with the given function at all but one point. Then find the limit of the
given function.
2 x2  x  3
lim
x 1
x 1
Find the limit analytically.
EX: lim
x 3
3 x
x2  9
( x  x)  x
x 3
x
2
EX:
lim
EX:
1
1

lim x  4 4
x 0
x
2
lim
Two special trigonometry limits:
x 1  2
x3
EX:
x 3
1  cos x
0
x 0
x
sin x
1
x 0
x
lim
lim
(1  cos x) 2
x 0
x2
EX:
lim
sin 4 x
x 0
5x
EX:
lim
EX:
lim
tan 2 x
x 0
x
EX:
lim
sin x
x 0 3 x
1.4
Learning Target: The student will be able to determine the intervals in which a function is
continuous or discontinuous and will also be able to determine if the discontinuities are removable or
non-removable. The student will find one-sided limits.
****A function is continuous on an interval if its graph is uninterrupted on that interval.
This function is continuous on (a,b)
These functions are discontinuous on (a,b)
Definition of continuity at a point c: A function f(x) is continuous at point c if 3 conditions are met:
1. f(c) is defined
2. lim f ( x ) exists
x c
3.
lim f ( x)  f (c)
x c
There are two types of discontinuities:
Removable: The problem can be fixed by simply coloring in the hole.
Non-removable: Can’t plug the hole
Discuss the continuity of the following . (where is it discontinuous? Is the disc remov or non-remov)
EX:
EX:
f ( x) 
x2 1
x 1
ONE-SIDED LIMITS: We only care what happens from 1 side instead of from both sides.
lim f ( x) is the limit coming in from the right.
lim f ( x) is the limit coming from the left.
x c
EX:
EX:
lim 
x 5
x c
3
x5
x 1 
x
lim f ( x) if f ( x)  

x 1
1  x x  1
EX:
EX:
lim
x 10
x  10
x  10
 x 2  4 x  6 x  2 
lim f ( x) if f ( x)   2

x2
 x  4 x  2 x  2 
1.4 con’t
Learning Target: The student will continue to discuss the continuity of functions.
Find the x values at which f(x) is NOT continuous. Are the discontinuities removable or non-removable?
EX:
EX:
f ( x) 
3
x2
2 x  3
f ( x)   2
x
EX:
f ( x) 
x
x 1
2
x  1

x  1
Find the constant a such that the function is continuous on the entire real line.
EX:
3x 3
x 1
f ( x)  

ax  5 x  1
1.5
Learning Target: The student will determine if a rational function has a hole or asymptote
discontinuity, therefore indentifying the location of vertical asymptotes. The student will then find
the limits of functions at these vertical asymptotes.
EX: will the function approach infinity or negative infinity as the function approaches 4 from the left, then
approaches 4 from the right?
f ( x) 
1
( x  4)2
a.
as x  4-
b. as x  4+
EX: same as above but as x approaches -2.
f ( x) 
1
x2
a.
as
x  -2-
b.
Find the vertical asymptote.
EX:
f ( x) 
4 x
x2  4
EX:
f ( x) 
as x
 -2+
2 x
x (1  x)
2
Where is the function discontinuous? Is the disc remov or non-remov? Is the disc a vert asymptote or
hole?
EX:
f ( x) 
x2  6 x  7
x 1