Math Problem Statement

Subpunctul 3

Subpunctul 3: Determine the twice differentiable function f such that f''(x) = 2x - 6, f(0) = 1, and f'(1) = 0.

Solution

In subpoint (3), we are given the following problem:

f(x)=2x6,f(0)=1,f(1)=0.f''(x) = 2x - 6, \quad f(0) = 1, \quad f'(1) = 0.

We need to determine the function f(x)f(x) that satisfies these conditions.

Step-by-Step Solution

  1. Integrate f(x)=2x6f''(x) = 2x - 6 to find f(x)f'(x): f(x)=(2x6)dx=x26x+C1,f'(x) = \int (2x - 6) \, dx = x^2 - 6x + C_1, where C1C_1 is a constant.

  2. Use f(1)=0f'(1) = 0 to find C1C_1: Substitute x=1x = 1 and f(1)=0f'(1) = 0: 0=(1)261+C1,0 = (1)^2 - 6 \cdot 1 + C_1, 0=16+C1,0 = 1 - 6 + C_1, C1=5.C_1 = 5. Thus, f(x)=x26x+5f'(x) = x^2 - 6x + 5.

  3. Integrate f(x)=x26x+5f'(x) = x^2 - 6x + 5 to find f(x)f(x): f(x)=(x26x+5)dx=x333x2+5x+C2,f(x) = \int (x^2 - 6x + 5) \, dx = \frac{x^3}{3} - 3x^2 + 5x + C_2, where C2C_2 is a constant.

  4. Use f(0)=1f(0) = 1 to find C2C_2: Substitute x=0x = 0 and f(0)=1f(0) = 1: 1=033302+50+C2,1 = \frac{0^3}{3} - 3 \cdot 0^2 + 5 \cdot 0 + C_2, C2=1.C_2 = 1. Thus, f(x)=x333x2+5x+1f(x) = \frac{x^3}{3} - 3x^2 + 5x + 1.

Final Answer

The function f(x)f(x) that satisfies all given conditions is: f(x)=x333x2+5x+1.f(x) = \frac{x^3}{3} - 3x^2 + 5x + 1.

Would you like a detailed explanation of any step?


Here are some related questions to explore:

  1. How do you verify that a solution satisfies initial conditions?
  2. What techniques can be used for integrating polynomial functions?
  3. How do higher-order derivatives influence the behavior of a function?
  4. What role do integration constants play in solving differential equations?
  5. How can you generalize this process for different forms of f(x)f''(x)?

Tip: When solving for a function with given derivative properties, work backwards from the highest derivative given, applying constants as you integrate each step.

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Math Problem Analysis

Mathematical Concepts

Differential Equations
Integration
Initial Conditions

Formulas

Integration of polynomial functions
Solving for constants using initial conditions

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 10-12