Math Problem Statement

Use the information about values of the functions and their derivatives to calculate 𝐻′(7),Hβ€²(7), where 𝐻(π‘₯)=π‘₯𝑔(π‘₯)𝑓(π‘₯).H(x)=xg(x)f(x). 𝑓(7)f(7) 𝑓′(7)fβ€²(7) 𝑔(7)g(7) 𝑔′(7)gβ€²(7) 33 βˆ’5βˆ’5 77 βˆ’4βˆ’4

(Give an exact answer. Use symbolic notation and fractions where needed.)

Solution

To find Hβ€²(7)H'(7) where H(x)=xβ‹…g(x)β‹…f(x)H(x) = x \cdot g(x) \cdot f(x), we will apply the product rule for differentiation.

We have:

H(x)=xβ‹…g(x)β‹…f(x)H(x) = x \cdot g(x) \cdot f(x)

To differentiate H(x)H(x), we treat it as the product of three factors: xx, g(x)g(x), and f(x)f(x).

Let’s apply the product rule step by step.

Step 1: Product Rule

For the product of three functions u(x)=xu(x) = x, v(x)=g(x)v(x) = g(x), and w(x)=f(x)w(x) = f(x), the derivative Hβ€²(x)H'(x) will be:

Hβ€²(x)=ddx(xβ‹…g(x)β‹…f(x))H'(x) = \frac{d}{dx} \left( x \cdot g(x) \cdot f(x) \right) Using the product rule for three functions, this expands as:

Hβ€²(x)=(xβ€²β‹…g(x)β‹…f(x))+(xβ‹…gβ€²(x)β‹…f(x))+(xβ‹…g(x)β‹…fβ€²(x))H'(x) = \left( x' \cdot g(x) \cdot f(x) \right) + \left( x \cdot g'(x) \cdot f(x) \right) + \left( x \cdot g(x) \cdot f'(x) \right)

Since ddx(x)=1\frac{d}{dx}(x) = 1, this simplifies to:

Hβ€²(x)=g(x)β‹…f(x)+xβ‹…gβ€²(x)β‹…f(x)+xβ‹…g(x)β‹…fβ€²(x)H'(x) = g(x) \cdot f(x) + x \cdot g'(x) \cdot f(x) + x \cdot g(x) \cdot f'(x)

Step 2: Substitute Values

We are given the following information:

f(7)=33,fβ€²(7)=βˆ’5,g(7)=7,gβ€²(7)=βˆ’4f(7) = 33, \quad f'(7) = -5, \quad g(7) = 7, \quad g'(7) = -4

Substituting these values into the expression for Hβ€²(7)H'(7):

Hβ€²(7)=g(7)β‹…f(7)+7β‹…gβ€²(7)β‹…f(7)+7β‹…g(7)β‹…fβ€²(7)H'(7) = g(7) \cdot f(7) + 7 \cdot g'(7) \cdot f(7) + 7 \cdot g(7) \cdot f'(7)

Now substitute the specific values:

Hβ€²(7)=7β‹…33+7β‹…(βˆ’4)β‹…33+7β‹…7β‹…(βˆ’5)H'(7) = 7 \cdot 33 + 7 \cdot (-4) \cdot 33 + 7 \cdot 7 \cdot (-5)

Step 3: Simplify

Now, calculate each term:

7β‹…33=2317 \cdot 33 = 231 7β‹…(βˆ’4)β‹…33=βˆ’9247 \cdot (-4) \cdot 33 = -924 7β‹…7β‹…(βˆ’5)=βˆ’2457 \cdot 7 \cdot (-5) = -245

Now, sum them together:

Hβ€²(7)=231+(βˆ’924)+(βˆ’245)H'(7) = 231 + (-924) + (-245)

Hβ€²(7)=231βˆ’924βˆ’245=βˆ’938H'(7) = 231 - 924 - 245 = -938

Thus, the exact value of Hβ€²(7)H'(7) is:

Hβ€²(7)=βˆ’938H'(7) = -938


Would you like more details or have any questions?

Here are 5 related questions:

  1. How does the product rule change when differentiating more than two functions?
  2. Can the product rule be extended to a chain of four or more functions?
  3. How would you approach differentiating a product that includes exponential functions?
  4. Why is the derivative of xx simply 1 in this context?
  5. How can you apply the product rule to functions involving trigonometric identities?

Tip: When applying the product rule, make sure to keep track of the derivatives of each factor separately to avoid mistakes in complex functions.

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Math Problem Analysis

Mathematical Concepts

Calculus
Differentiation
Product Rule

Formulas

H(x) = x * g(x) * f(x)
Product rule for three functions: H'(x) = g(x) * f(x) + x * g'(x) * f(x) + x * g(x) * f'(x)

Theorems

Product Rule of Differentiation

Suitable Grade Level

Grades 11-12 (Advanced Calculus)