MATHEMATICS - THEORY
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Function |
The quantity relationship of
function y = x2 + x + 1
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If the quantity of y is determined
by another value x, then y is a function of x. If f denotes the
function, then the formula y = f(x) indicate y depends on x. Thus y is
a dependent variable and x is a independent variable. An
example
of a function would be:
y = x2 + x + 1
The diagram on the left shows that the quantity of y which is equal to
x2 + x + 1
depends on the value of x.
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Limit of a Function
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If for each positive ε, no
matter how small, there is a corresponding positive δ such
that if
then
In this situation, the limit of f(x) is A as x approaches
a, and it can be written as:
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Limits Involving Infinity
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In this segment, three kind of situations will be discussed. |
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The limit of f(x) is infinity
when x approaches 1 |
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- The limit of f(x) is ∞ as x approaches a if for each number B, no matter how large, there is a corresponding positive δ, such that if
then
f(x) > B
Its notation is
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The limit of f(x) is 1
when x approaches +∞ |
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- The limit of f(x) is A as x approaches ∞ if
for each positive ε, no matter how small,
there is a corresponding B such that if
x > B
then
Its notation is
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The limit of f(x) is -∞ when x
approaches
-∞ |
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- The limit of f(x) is -∞ as x approaches -∞ if for each number B, no matter how large, there is a corresponding C, such that if
x< -C
then
f(x) < -B
Its notation is
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Summary
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Summary
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This section introduces limit of a function and three cases involving infinity. When discussing limit of a function, it must be the limit of a specific point. |
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