Khác biệt giữa các bản “Đạo hàm riêng”

n (r2.7.2) (Bot: Thêm en:Partial derivative)
Kí hiệu của đạo hàm riêng là''[[∂]]''. Kí hiệu này được giới thiệu bởi [[Adrien-Marie Legendre]]và được chấp nhận rộng rãi sau khi nó được giới thiệu lại bởi [[Carl Gustav Jacob Jacobi]].<ref>{{cite web|url=http://jeff560.tripod.com/calculus.html|title=Earliest Uses of Symbols of Calculus|author=Jeff Miller|date=2009-06-14|work=Earliest Uses of Various Mathematical Symbols|accessdate=2010-02-20}}</ref>
 
==Introduction==
Suppose that ''ƒ'' is a function of more than one variable. For instance,
 
:<math>z = f(x, y) = \,\! x^2 + xy + y^2.\,</math>
 
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The [[graph of a function|graph]] of this function defines a [[surface]] in [[Euclidean space]]. To every point on this surface, there are an infinite number of [[tangent line]]s. Partial differentiation is the act of choosing one of these lines and finding its [[slope]]. Usually, the lines of most interest are those that are parallel to the ''xz''-plane, and those that are parallel to the ''yz''-plane.
 
To find the slope of the line tangent to the function at {{nowrap|(1, 1, 3)}} that is parallel to the ''xz''-plane, the ''y'' variable is treated as constant. The graph and this plane are shown on the right. On the graph below it, we see the way the function looks on the plane {{nowrap|''y'' {{=}} 1}}. By finding the [[derivative]] of the equation while assuming that ''y'' is a constant, the slope of ''ƒ''
==Definition==
=== Basic definition ===
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