Questions: Compute (T2(x)) at (x=0.7) for (y=e^x) and use a calculator to compute the error (lefte^x-T2(x)right) at (x=1.4). [ T2(x)=square mathrmm ] [ lefte^x-T2(x)right=square ]

Compute (T2(x)) at (x=0.7) for (y=e^x) and use a calculator to compute the error (lefte^x-T2(x)right) at (x=1.4).
[ T2(x)=square mathrmm ]
[ lefte^x-T2(x)right=square ]
Transcript text: Compute $T_{2}(x)$ at $x=0.7$ for $y=e^{x}$ and use a calculator to compute the error $\left|e^{x}-T_{2}(x)\right|$ at $x=1.4$. \[ \begin{array}{l} T_{2}(x)=\square \mathrm{m} \\ \left|e^{x}-T_{2}(x)\right|=\square \\ \hline \end{array} \]
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Solution

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Solution Steps

To solve this problem, we need to compute the second-degree Taylor polynomial \( T_2(x) \) for the function \( y = e^x \) at a given point. The Taylor polynomial is given by:

\[ T_2(x) = f(a) + f'(a)(x-a) + \frac{f''(a)}{2}(x-a)^2 \]

where \( f(x) = e^x \), and \( a \) is the point around which we are expanding the polynomial. For this problem, we assume \( a = 0 \) (Maclaurin series). After computing \( T_2(x) \) at \( x = 0.7 \), we calculate the error at \( x = 1.4 \) using the formula:

\[ \text{Error} = \left| e^{1.4} - T_2(1.4) \right| \]

Step 1: Compute \( T_2(0.7) \)

To compute the second-degree Taylor polynomial \( T_2(x) \) for \( y = e^x \) at \( x = 0.7 \), we use the formula:

\[ T_2(x) = f(0) + f'(0)(x - 0) + \frac{f''(0)}{2}(x - 0)^2 \]

Calculating the values:

  • \( f(0) = e^0 = 1 \)
  • \( f'(0) = e^0 = 1 \)
  • \( f''(0) = e^0 = 1 \)

Substituting these into the polynomial:

\[ T_2(0.7) = 1 + 1 \cdot (0.7) + \frac{1}{2} \cdot (0.7)^2 = 1 + 0.7 + 0.245 = 1.9449999999999998 \]

Thus, we have:

\[ T_2(0.7) \approx 1.945 \]

Step 2: Compute the Error at \( x = 1.4 \)

Next, we compute the error between the actual value of \( e^{1.4} \) and the Taylor polynomial \( T_2(1.4) \). First, we calculate \( T_2(1.4) \):

\[ T_2(1.4) = f(0) + f'(0)(1.4 - 0) + \frac{f''(0)}{2}(1.4 - 0)^2 \]

Substituting the values:

\[ T_2(1.4) = 1 + 1 \cdot (1.4) + \frac{1}{2} \cdot (1.4)^2 = 1 + 1.4 + 0.98 = 3.38 \]

Now, we compute the actual value of \( e^{1.4} \):

\[ e^{1.4} \approx 4.0552 \]

The error is given by:

\[ \text{Error} = \left| e^{1.4} - T_2(1.4) \right| = \left| 4.0552 - 3.38 \right| \approx 0.6752 \]

Final Answer

The results are:

  • \( T_2(0.7) \approx 1.945 \)
  • Error at \( x = 1.4 \approx 0.6752 \)

Thus, the final answers are:

\[ \boxed{T_2(0.7) \approx 1.945} \] \[ \boxed{\text{Error} \approx 0.6752} \]

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