In this section, we will learn about:
Vector functions and drawing their corresponding space curve
In general, a function is a rule that assigns to each element in the domain an element in the range.
A vector-valued function, or vector function, is simply a function whose:
§ Domain is a set of real numbers.
§ Range is a set of vectors.
We are most interested in vector functions r whose values are three-dimensional (3-D) vectors.
§ This means that, for every number t
in the domain of r, there is a unique
vector in V3 denoted by r(t).
If f(t), g(t), and h(t) are the components of
the vector r(t), then f, g, and h are real-valued functions called the component functionsof r.
Wecan write:
r(t) = ‹f(t), g(t), h(t)› = f(t) i + g(t) j + h(t) k
We usually use the letter t to denote
the independent variable because
it represents time in most applications
of vector functions.
If then the component functions are:
By our usual convention, the domain of r consists of all values of t for which the expression for r(t) is defined.
§ The expressions t3, ln(3 – t), and are all defined when 3 – t > 0 and t ≥ 0.
§ Therefore, the domain of r is the interval [0, 3).
The limitof a vector function r is defined by taking the limits of its component functions as follows.
If r(t) = ‹f(t), g(t), h(t)›, then provided the limits of the component functions exist.
If , this definition is equivalent to saying that the length and direction of the vector r(t) approach the length and direction of the vector L.
Find where
According to Definition 1, the limit of r is
the vector whose components are the limits
of the component functions of r:
» Danh sách Tập tin đính kèm:
» Tin mới nhất:
» Các tin khác: