Math Problem Statement

Find the Taylor polynomial T2(x) and compute the error |f(x) - T2(x)| for the given values of a and x. f(x) = e^(sin(x)), a = π/2, x = 1.3 (Round your answer to six decimal places.)

Solution

To solve this problem, we need to find the second-order Taylor polynomial T2(x)T_2(x) for the function f(x)=esin(x)f(x) = e^{\sin(x)} centered at a=π2a = \frac{\pi}{2}, and then compute the error f(1.3)T2(1.3)|f(1.3) - T_2(1.3)|.

Step 1: Taylor Polynomial Formula

The Taylor series for a function f(x)f(x) centered at aa is given by: Tn(x)=f(a)+f(a)(xa)+f(a)2!(xa)2++f(n)(a)n!(xa)nT_n(x) = f(a) + f'(a)(x - a) + \frac{f''(a)}{2!}(x - a)^2 + \dots + \frac{f^{(n)}(a)}{n!}(x - a)^n Since we want the second-order polynomial T2(x)T_2(x), we will need f(a)f(a), f(a)f'(a), and f(a)f''(a).

Step 2: Calculate f(a)f(a), f(a)f'(a), and f(a)f''(a)

  1. f(x)=esin(x)f(x) = e^{\sin(x)}

    • f(a)=f(π2)=esin(π2)=e1=ef(a) = f\left(\frac{\pi}{2}\right) = e^{\sin\left(\frac{\pi}{2}\right)} = e^1 = e.
  2. First derivative f(x)f'(x)

    • By the chain rule, f(x)=esin(x)cos(x)f'(x) = e^{\sin(x)} \cdot \cos(x).
    • So, f(π2)=esin(π2)cos(π2)=e0=0f'\left(\frac{\pi}{2}\right) = e^{\sin\left(\frac{\pi}{2}\right)} \cdot \cos\left(\frac{\pi}{2}\right) = e \cdot 0 = 0.
  3. Second derivative f(x)f''(x)

    • Using the product rule on f(x)=esin(x)cos(x)f'(x) = e^{\sin(x)} \cdot \cos(x): f(x)=esin(x)cos(x)cos(x)+esin(x)(sin(x))=esin(x)(cos2(x)sin(x)).f''(x) = e^{\sin(x)} \cdot \cos(x) \cdot \cos(x) + e^{\sin(x)} \cdot (-\sin(x)) = e^{\sin(x)} (\cos^2(x) - \sin(x)).
    • Therefore, f(π2)=esin(π2)(cos2(π2)sin(π2))=e(01)=ef''\left(\frac{\pi}{2}\right) = e^{\sin\left(\frac{\pi}{2}\right)} \cdot (\cos^2\left(\frac{\pi}{2}\right) - \sin\left(\frac{\pi}{2}\right)) = e \cdot (0 - 1) = -e.

Step 3: Construct T2(x)T_2(x)

Now we can plug in these values into the Taylor polynomial: T2(x)=f(a)+f(a)(xa)+f(a)2!(xa)2T_2(x) = f(a) + f'(a)(x - a) + \frac{f''(a)}{2!}(x - a)^2 Substituting the values we found: T2(x)=e+0(xπ2)+e2(xπ2)2=ee2(xπ2)2T_2(x) = e + 0 \cdot (x - \frac{\pi}{2}) + \frac{-e}{2} (x - \frac{\pi}{2})^2 = e - \frac{e}{2} (x - \frac{\pi}{2})^2

Step 4: Evaluate T2(1.3)T_2(1.3)

  1. Substitute x=1.3x = 1.3 and a=π21.5708a = \frac{\pi}{2} \approx 1.5708: T2(1.3)=ee2(1.31.5708)2T_2(1.3) = e - \frac{e}{2} (1.3 - 1.5708)^2
  2. Calculate 1.31.57080.27081.3 - 1.5708 \approx -0.2708.
  3. Square this result: (0.2708)20.0733(-0.2708)^2 \approx 0.0733.
  4. Multiply by e2-\frac{e}{2}: e2×0.07330.0998-\frac{e}{2} \times 0.0733 \approx -0.0998.
  5. Therefore, T2(1.3)e0.09982.6183T_2(1.3) \approx e - 0.0998 \approx 2.6183 (using e2.71828e \approx 2.71828).

This value should be accurate to six decimal places as required.

Step 5: Compute the Error f(1.3)T2(1.3)|f(1.3) - T_2(1.3)|

  1. Calculate f(1.3)=esin(1.3)f(1.3) = e^{\sin(1.3)}:
    • Find sin(1.3)0.9636\sin(1.3) \approx 0.9636.
    • Then f(1.3)=e0.96362.6215f(1.3) = e^{0.9636} \approx 2.6215.
  2. Now, the error f(1.3)T2(1.3)|f(1.3) - T_2(1.3)|: 2.62152.6183=0.0032|2.6215 - 2.6183| = 0.0032

Thus, the answers should be approximately:

  • T2(1.3)2.6183T_2(1.3) \approx 2.6183
  • f(1.3)T2(1.3)0.0032|f(1.3) - T_2(1.3)| \approx 0.0032, or 3.2×1033.2 \times 10^{-3} when expressed in scientific notation.

Would you like further details or have any questions?

Related Questions

  1. How is the error in Taylor polynomials calculated and estimated?
  2. What happens to the accuracy of Taylor polynomials as the order increases?
  3. How is the Taylor polynomial different from the Maclaurin polynomial?
  4. Why does the Taylor polynomial use derivatives at a point aa as the basis of approximation?
  5. How can one calculate higher-order derivatives for more complex functions in Taylor series?

Tip:

When approximating a function near a given point, using the Taylor polynomial centered at that point usually gives a more accurate approximation than using a polynomial centered elsewhere.

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Math Problem Analysis

Mathematical Concepts

Calculus
Taylor Series
Approximation

Formulas

Taylor series expansion: T_n(x) = f(a) + f'(a)(x - a) + (f''(a)/2!)(x - a)^2 + ... + (f^(n)(a)/n!)(x - a)^n
Error calculation: |f(x) - T_n(x)|

Theorems

Taylor's Theorem

Suitable Grade Level

College Calculus