65.8k views
0 votes
Use the Lagrange Error Bound for P

n

(x) to find a bound for the error in approximating the quantity with a third-degree Taylor polynomial for the given function f(x) about x=0. sin(0.3)⋅f(x)=sinx Round your answer to six decimal places.

User Bevin
by
8.2k points

1 Answer

3 votes

Answer:

To find a bound for the error in approximating the quantity with a third-degree Taylor polynomial for the function f(x) = sin(x) about x = 0, we can use the Lagrange Error Bound for Pn(x).

The Lagrange Error Bound formula is given by:

|f(x) - Pn(x)| ≤ M * |x - a|^(n+1) / (n+1)!

Where:

- f(x) is the given function

- Pn(x) is the nth degree Taylor polynomial approximation of f(x)

- M is the maximum value of the (n+1)th derivative of f(x) on the interval [a, x]

- x is the value at which we want to approximate f(x)

- a is the center of the Taylor polynomial approximation

For this problem, we want to find the error in approximating sin(0.3) using a third-degree Taylor polynomial about x = 0.

Since we are using a third-degree Taylor polynomial, n = 3. The center of the approximation is a = 0.

To find the bound, we need to find the maximum value of the fourth derivative of f(x) = sin(x) on the interval [0, 0.3]. We can do this by finding the maximum value of the absolute value of the fourth derivative of sin(x) on that interval.

Taking the derivative of sin(x) four times, we get:

f''''(x) = -sin(x)

To find the maximum value of -sin(x) on the interval [0, 0.3], we can compare the values at the endpoints and any critical points in between.

At x = 0, -sin(x) = 0.

At x = 0.3, -sin(x) = -sin(0.3) ≈ -0.29552.

Therefore, the maximum value of -sin(x) on the interval [0, 0.3] is approximately 0.29552.

Now we can plug these values into the Lagrange Error Bound formula:

|f(0.3) - P3(0.3)| ≤ M * |0.3 - 0|^4 / (3+1)!

Since f(x) = sin(x) and P3(x) is the third-degree Taylor polynomial approximation of f(x) about x = 0, we have:

|sin(0.3) - P3(0.3)| ≤ 0.29552 * |0.3 - 0|^4 / 4!

Simplifying further:

|sin(0.3) - P3(0.3)| ≤ 0.29552 * 0.3^4 / 24

|sin(0.3) - P3(0.3)| ≤ 0.002087

Therefore, the bound for the error in approximating sin(0.3) with a third-degree Taylor polynomial about x = 0 is approximately 0.002087.

Remember to round your answer to six decimal places.

User Vikram Garg
by
7.5k points

Related questions

Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories