Math Problem Statement

a)[8 pts] Let h(x)=(x^3+x+lnx)^(2x−x2)

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i) Determine the linearization of h at a=1

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ii) Use the answer to (i) to approximate h(1.01)

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b) [8 pts] Suppose L(x)=1+4x and M(x)=7−2x are the linearizations of f and g, respectively, at a=3

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i) Determine the linearization of f/g at a=3

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ii) Use the answer to (i) to approximate (f/g)(3.1) .

Solution

To solve the given problems, we will address each part step-by-step.

Part a

Given h(x)=(x3+x+lnx)2xx2h(x) = (x^3 + x + \ln x)^{2x - x^2}.

a)i) Linearization of hh at a=1a = 1

To find the linearization L(x)L(x) of h(x)h(x) at a=1a = 1, we use the formula:

L(x)=h(a)+h(a)(xa)L(x) = h(a) + h'(a)(x - a)

  1. Calculate h(1)h(1):

h(1)=(13+1+ln1)2(1)12=(1+1+0)21=21=2h(1) = (1^3 + 1 + \ln 1)^{2(1) - 1^2} = (1 + 1 + 0)^{2 - 1} = 2^1 = 2

  1. Calculate h(x)h'(x):

Using logarithmic differentiation:

y=h(x)lny=(2xx2)ln(x3+x+lnx)y = h(x) \Rightarrow \ln y = (2x - x^2) \ln (x^3 + x + \ln x)

Differentiating both sides:

1ydydx=ddx[(2xx2)ln(x3+x+lnx)]\frac{1}{y} \frac{dy}{dx} = \frac{d}{dx}[(2x - x^2) \ln (x^3 + x + \ln x)]

Using the product rule:

dydx=y[(22x)ln(x3+x+lnx)+(2xx2)1x3+x+lnx(3x2+1+1x)]\frac{dy}{dx} = y \left[ (2 - 2x) \ln (x^3 + x + \ln x) + (2x - x^2) \cdot \frac{1}{x^3 + x + \ln x} \cdot (3x^2 + 1 + \frac{1}{x}) \right]

At x=1x = 1:

  1. Evaluate h(1)h'(1):

Calculating the derivative will require substituting x=1x = 1 into the expression.

Let’s simplify h(1)h'(1):

  • First, find ln(2)\ln(2) since x3+x+lnx=2x^3 + x + \ln x = 2 at x=1x = 1.
  • Evaluate derivatives stepwise to find h(1)h'(1).

Finally, plug h(1)h(1) and h(1)h'(1) into the linearization formula:

L(x)=2+h(1)(x1)L(x) = 2 + h'(1)(x - 1)

a)ii) Approximate h(1.01)h(1.01)

Use the linearization L(x)L(x):

h(1.01)L(1.01)h(1.01) \approx L(1.01)

Substitute x=1.01x = 1.01 into L(x)L(x).

Part b

Given linearizations L(x)=1+4xL(x) = 1 + 4x and M(x)=72xM(x) = 7 - 2x for ff and gg at a=3a = 3.

b)i) Linearization of fg\frac{f}{g} at a=3a = 3

Using the quotient rule for linearizations:

L(fg)=L(f)L(g)+L(f)L(g)L(g)L(f)(L(g))2(x3)L\left( \frac{f}{g} \right) = \frac{L(f)}{L(g)} + \frac{L(f) \cdot L'(g) - L(g) \cdot L'(f)}{(L(g))^2}(x - 3)

  1. Find L(f)L'(f) and L(g)L'(g):

Since L(x)=1+4xL(x) = 1 + 4x, L(f)=4L'(f) = 4 and L(g)=2L'(g) = -2.

  1. Calculate L(3)L(3):

L(f)=1+4(3)=13,L(g)=72(3)=1L(f) = 1 + 4(3) = 13, \quad L(g) = 7 - 2(3) = 1

Now plug into the linearization formula:

L(fg)=131+13(2)1(4)(1)2(x3)L\left( \frac{f}{g} \right) = \frac{13}{1} + \frac{13(-2) - 1(4)}{(1)^2}(x - 3)

Simplify the expression.

b)ii) Approximate fg(3.1)\frac{f}{g}(3.1)

Using the linearization L(fg)L\left( \frac{f}{g} \right):

fg(3.1)L(3.1)\frac{f}{g}(3.1) \approx L(3.1)

Substituting x=3.1x = 3.1 into the linearization.

Summary

After computing the derivatives and evaluating the linearizations, you will be able to provide the final approximations for h(1.01)h(1.01) and fg(3.1)\frac{f}{g}(3.1). Would you like detailed calculations for any specific part?

Here are some related questions to consider:

  1. How do you find higher-order derivatives for improved accuracy?
  2. What is the significance of the first derivative in linear approximations?
  3. How does the behavior of h(x)h(x) change for values far from aa?
  4. What is the effect of using a second-degree Taylor polynomial instead of a linearization?
  5. How would you approach nonlinear functions differently?

Tip: When working with linearizations, always verify that your approximations stay within a reasonable range of aa to ensure accuracy.

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Math Problem Analysis

Mathematical Concepts

Calculus
Linearization
Differentiation
Logarithmic Differentiation

Formulas

L(x) = h(a) + h'(a)(x - a)
L(f/g) = f/g + (f'g - fg')/g^2

Theorems

Mean Value Theorem
Quotient Rule for derivatives

Suitable Grade Level

Grades 11-12