Math Problem Statement

consider the funciton f(x)=2x^2-5x+5,a. find the linear approximation, L(x) at x=3. b. use your function from part b to approximate f(3.2)

Solution

To solve this problem, we need to follow these steps:

Part (a): Find the linear approximation L(x)L(x) at x=3x = 3

The linear approximation of a function f(x)f(x) at a point x=ax = a is given by: L(x)=f(a)+f(a)(xa)L(x) = f(a) + f'(a)(x - a)

First, we need to find f(3)f(3): f(x)=2x25x+5f(x) = 2x^2 - 5x + 5 f(3)=2(3)25(3)+5f(3) = 2(3)^2 - 5(3) + 5 f(3)=2(9)15+5f(3) = 2(9) - 15 + 5 f(3)=1815+5=8f(3) = 18 - 15 + 5 = 8

Next, we need to find the derivative f(x)f'(x): f(x)=ddx(2x25x+5)f'(x) = \frac{d}{dx}(2x^2 - 5x + 5) f(x)=4x5f'(x) = 4x - 5

Then, find f(3)f'(3): f(3)=4(3)5f'(3) = 4(3) - 5 f(3)=125=7f'(3) = 12 - 5 = 7

Now, we can write the linear approximation L(x)L(x) at x=3x = 3: L(x)=f(3)+f(3)(x3)L(x) = f(3) + f'(3)(x - 3) L(x)=8+7(x3)L(x) = 8 + 7(x - 3) L(x)=8+7x21L(x) = 8 + 7x - 21 L(x)=7x13L(x) = 7x - 13

Part (b): Use the linear approximation to approximate f(3.2)f(3.2)

Using the linear approximation L(x)=7x13L(x) = 7x - 13: L(3.2)=7(3.2)13L(3.2) = 7(3.2) - 13 L(3.2)=22.413L(3.2) = 22.4 - 13 L(3.2)=9.4L(3.2) = 9.4

Therefore, the approximation of f(3.2)f(3.2) using the linear approximation is 9.4.

Would you like further details or have any questions?

Here are some related questions you might be interested in:

  1. How do you find the second derivative of a function?
  2. What is the purpose of linear approximation in calculus?
  3. Can you explain the concept of Taylor series?
  4. How do you determine the concavity of a function?
  5. What are some real-world applications of linear approximations?

Tip: When approximating functions, the closer your point of approximation is to the given point, the more accurate your approximation will be.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Calculus
Linear Approximation
Derivatives

Formulas

Linear approximation formula L(x) = f(a) + f'(a)(x - a)
Derivative formula f'(x) = 4x - 5

Theorems

-

Suitable Grade Level

Advanced High School