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Tansformation of Function

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Tansformation of Function

(Stewarts Algebra and Trigonometry)

Vertical Shifting

Adding a constant to function shifts its graph vertically upward if the constant is
positive and downward if its negative

Hence: y = f(x) + c is c units above the y-coordinate of the corresponding point on


the graph of y = f(x). Similarly, we obtain the graph of y = f(x) − c by shifting the
graph of y = f(x) downward by c units

Example
f(x) = x2 + 1
f(x) = x2

f(x) = x2 − 2

Horizontal shift of the graph

The graph of y = f(x + c) is the graph of y = f(x) shifted to the left c units
The graph of y = f(x − c) is the graph of y = f(x) shifted to the right c units

Example
1. Graph f(x) = (x − 4)2 and f(x) = (x + 1)2

f(x) = (x + 1)2 f(x) = x2 f(x) = (x − 4)2


Combining horizontal and vertical shift
f(x) = (x − 1)2 + 3

Graph f(x) = (x − 1)2 + 3


f(x) = (x − 1)2
f(x) = x2

Reflecting graph

To graph y =− f(x) reflect the graph of y = f(x) in the x-axis


To graph y = f( − x) reflect the graph of y = f(x) in the y-axis

y = f(x)
y = f(x)

y = f( − x)

y =− f(x)

Example
Graph f(x) =− x2 f(x) = x2

f(x) =− x2
Vertical Stretching and Shrinking
To graph y = cf(x)

If c > 1 stretch the graph of y = f(x) vertically by a factor of C


If c <1, shrink the graph of y = f(x) vertically by a factor of C

y = cf(x) y = f(x)
y = f(x)
y = cf(x)

Example g(x) = 3x2


f(x) = x2
1 2
h(x) = x
3

1
Graph the function y = 3 − 2 (x − 1)2
y = x2 y = (x − 1)2

1
y = 3 − (x − 1)2
2

1
y =− (x − 1)2
2
Horizontal shrinking and stretching of Graphs

1
If c > 1, shrink the graph of y = f(x) horizontally by a factor of �
1
If 0 < c < 1, sketch the graph of y = f(x) horizontally by a factor of �

y = f(cx)
y = f(x)

c>1

y = f(x)
y = f(cx)

0<c<1

y = f(x)
y = f(2x)

1
y = f( x)
2

Transformation of trigonometric function

f(x) = 1 + cosx
f(x) =− sinx
1
g(x) = sinx
2
f(x) = cos2x

f(x) = cosx + 1

π 2π 3π 4π

f(x) = cos2x f(x) = cosx


f(x) = sinx
1
f(x) = sin x
2
π 2π 3π 4π

f(x) =− sinx

Hence with sine and cosine curve


y = asink(x − b)
y = acosk(x − b)
Amplitude=|a|

Period= k
And phase shift of b

Graph of Transformation of tangent and cotangent

 Graph the function 4tanx, − tanx

� � 3� π
4 2 4

π
Graph the function y = tan2x and y = tan2(x − 3 )

� � 3� π
4 2 4

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