Linear Approximation

camira

New member
Joined
Dec 7, 2014
Messages
2
Hello,
I have a question regarding linear approximation.
I think I understand the overall concept, but recently there was a solution posted for a question I had on a midterm that I am unsure about.
Question:
Find a linear approximation of the function f(x)= (x-1)^1/4 at a=2 and use it to approximate (1.3)^1/4
Solution:
L(x)=f(a)+f'(a)(x-a)
=1+1/4(x-2)
L(2.3)=1+1/4(2.3-2)
=1.075

I really don't understand why 2.3 would be substituted into the equation instead of 1.3....any explanation to this would be much appreciated!
 
Hello,
I have a question regarding linear approximation.
I think I understand the overall concept, but recently there was a solution posted for a question I had on a midterm that I am unsure about.
Question:
Find a linear approximation of the function f(x)= (x-1)^1/4 at a=2 and use it to approximate (1.3)^1/4
Solution:
L(x)=f(a)+f'(a)(x-a)
=1+1/4(x-2)
L(2.3)=1+1/4(2.3-2)
=1.075

I really don't understand why 2.3 would be substituted into the equation instead of 1.3....any explanation to this would be much appreciated!
If x = 2.3 then
f(2.3) = (2.3 - 1)1/4 = (1.3)1/4
 
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