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Functions and Limits

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Calculus and Analytical Geometry
MTH101
LECTUER ­ 6
Functions and Limits
Although f is the symbol most common
In this lecture we shall discuss:
ly used to denote a function, any symbol can
be used. Thus
Example
y=4x+1 defines y as a function of x
because each value assigned to x determines
exactly one value of y.
Example
In the following example y is not a function
of x, as each value assigned to x determines
two values of y.
If we use the letter f to denote a function,
then the equation
Mth101
Page 17
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Calculus and Analytical Geometry
Functions and Limits
Example
x0
x
Exampl
x =⎨
e
⎩- x
x<0
Natural Domain
If a function is defined by a formula and
there is no domain explicitly stated, then it is
understood that the domain consists of all real
numbers for which the formula makes sense,
and the function has a real value. This is called
the natural domain of the function.
Exampl
e
Mth101
Page 18