Linear Approximations

Definition (Linear Approximation) The approximation

linear approximation _gr_1.gif]

is called the linear approximation of linear approximation _gr_2.gif] at linear approximation _gr_3.gif] and the function

linear approximation _gr_4.gif]

is called the linearization of linear approximation _gr_5.gif] at linear approximation _gr_6.gif]

    The equation of the tangent line to the curve linear approximation _gr_7.gif] at linear approximation _gr_8.gif] is

linear approximation _gr_9.gif]

which is linear approximation _gr_10.gif] so that in fact we have linear approximation _gr_11.gif] Thus when using differentials to approximate, that is, when using   linear approximation _gr_12.gif] to approximate we are using the tangent line at linear approximation _gr_13.gif] as an approximation to the curve linear approximation _gr_14.gif] when linear approximation _gr_15.gif] is near linear approximation _gr_16.gif]

Example (Linear Approximation) Find the linearization for the following functions at the given value.

(a) Find the linearization of   linear approximation _gr_17.gif] at linear approximation _gr_18.gif]

    Solution. The linearization of the function linear approximation _gr_19.gif]at linear approximation _gr_20.gif] is

linear approximation _gr_21.gif]

linear approximation _gr_22.gif]

linear approximation _gr_23.gif]

Therefore, we have the linear approximation linear approximation _gr_24.gif] for when linear approximation _gr_25.gif] is near 0.

(b)
Find the linearization of   linear approximation _gr_26.gif] at linear approximation _gr_27.gif]

    Solution. The linearization of the function linear approximation _gr_28.gif]at linear approximation _gr_29.gif] is

linear approximation _gr_30.gif]

linear approximation _gr_31.gif]

linear approximation _gr_32.gif]

Therefore, we have the linear approximation linear approximation _gr_33.gif] for when linear approximation _gr_34.gif] is near 0. linear approximation _gr_35.gif]

Cite this as:
Linear Approximation
Published by Library of Math -- Online math organized by subject into topics.
Written by Smith, David A.
http://www.libraryofmath.com/linear-approximation.html
 
    
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