
G
lim
x!a
½f ðxÞgðxÞ5 lim
x!a
f ðxÞlim
x!a
gðxÞ
G
lim
x!a
f ðxÞ
gðxÞ
5
lim
x!a
f ðxÞ
lim
x!a
gðxÞ
; if lim
x!a
gðxÞ 6¼ 0
G
lim
x!a
½kf ðxÞ5 k lim
x!a
f ðxÞ
G
lim
x!a
f ðgðxÞÞ5 f ðlim
x!a
gðxÞÞ
G
lim
x!a
f ðxÞ5 f ðaÞ, if the function f(x) is continuous at x 5 a
G
lim
x!0
sin x
x
5 1
G
lim
x!0
tan x
x
5 1
G
lim
x!0
sin
21
x
x
5 1
G
lim
x!0
tan
21
x
x
5 1
G
lim
x!0
lnð1 1 xÞ
x
5 1
G
lim
x!N
11
1
x
x
5 e
G
lim
x!N
11
k
x
x
5 e
k
G
lim
x!0
a
x
5 1
5.3 Definition and Properties of the Derivative
Functions: f, g, y, u, v
Independent variable: x
Real constant: k
Angle: α
G
y
0
ðxÞ5 lim
Δx!0
f ðx 1 ΔxÞ2 f ðxÞ
Δx
5 lim
Δx!0
Δy
Δx
5
dy
dx
G
dy
dx
5 tan α
67Calculus