Math Problem Statement

Soit la fonction f(x) = (-6x + 7) * e^(5x - 7). Déterminer la dérivée de f.

Solution

We are asked to find the derivative of the function f(x)=(6x+7)e5x7f(x) = (-6x + 7)e^{5x - 7}.

Step-by-step solution:

This function is a product of two parts:

  1. (6x+7)(-6x + 7)
  2. e5x7e^{5x - 7}

To differentiate, we apply the product rule for derivatives. The product rule states:

(fg)=fg+fg(f \cdot g)' = f' \cdot g + f \cdot g'

Let:

  • f1(x)=(6x+7)f_1(x) = (-6x + 7)
  • f2(x)=e5x7f_2(x) = e^{5x - 7}

Now, we calculate the derivatives of both parts:

  1. Derivative of f1(x)=(6x+7)f_1(x) = (-6x + 7): f1(x)=6f_1'(x) = -6

  2. Derivative of f2(x)=e5x7f_2(x) = e^{5x - 7}: Use the chain rule here. The derivative of eue^{u} is euue^{u} \cdot u', where u=5x7u = 5x - 7. f2(x)=e5x75=5e5x7f_2'(x) = e^{5x - 7} \cdot 5 = 5e^{5x - 7}

Now, applying the product rule:

f(x)=f1(x)f2(x)+f1(x)f2(x)f'(x) = f_1'(x) \cdot f_2(x) + f_1(x) \cdot f_2'(x) Substitute the values: f(x)=(6)e5x7+(6x+7)5e5x7f'(x) = (-6) \cdot e^{5x - 7} + (-6x + 7) \cdot 5e^{5x - 7}

Simplifying: f(x)=6e5x7+5(6x+7)e5x7f'(x) = -6e^{5x - 7} + 5(-6x + 7)e^{5x - 7}

Factor out e5x7e^{5x - 7}: f(x)=e5x7(6+5(6x+7))f'(x) = e^{5x - 7} \left( -6 + 5(-6x + 7) \right)

Simplify the expression inside the parentheses: f(x)=e5x7(630x+35)f'(x) = e^{5x - 7} \left( -6 - 30x + 35 \right) f(x)=e5x7(30x+29)f'(x) = e^{5x - 7} \left( -30x + 29 \right)

Thus, the derivative is: f(x)=(30x+29)e5x7f'(x) = (-30x + 29) e^{5x - 7}

Would you like more details, or do you have any questions?


Here are five related questions to deepen your understanding:

  1. How does the product rule apply to more complex functions?
  2. What is the significance of the chain rule in differentiating exponential functions?
  3. Can you differentiate f(x)=x2e3xf(x) = x^2 e^{3x} using a similar approach?
  4. How does factoring out common terms simplify derivative expressions?
  5. How would you interpret the derivative of this function graphically?

Tip: Always look for common terms in your derivative expression to simplify and factorize where possible.

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Math Problem Analysis

Mathematical Concepts

Differentiation
Product Rule
Exponential Functions
Chain Rule

Formulas

Product rule: (f * g)' = f' * g + f * g'
Chain rule: d/dx [e^(u)] = e^(u) * u'

Theorems

Product Rule
Chain Rule

Suitable Grade Level

Undergraduate