If f(x) = sin(x) + cos(x), what is f'(π/4)?

Practice Questions

Q1
If f(x) = sin(x) + cos(x), what is f'(π/4)?
  1. 0
  2. √2
  3. 1
  4. √2/2

Questions & Step-by-Step Solutions

If f(x) = sin(x) + cos(x), what is f'(π/4)?
  • Step 1: Identify the function f(x) = sin(x) + cos(x).
  • Step 2: Find the derivative of f(x), which is f'(x) = cos(x) - sin(x).
  • Step 3: Substitute x = π/4 into the derivative: f'(π/4) = cos(π/4) - sin(π/4).
  • Step 4: Calculate cos(π/4) and sin(π/4). Both are equal to √2/2.
  • Step 5: Substitute the values into the equation: f'(π/4) = √2/2 - √2/2.
  • Step 6: Simplify the expression: f'(π/4) = 0.
  • Differentiation of Trigonometric Functions – The question tests the ability to differentiate the function f(x) = sin(x) + cos(x) and evaluate the derivative at a specific point.
  • Evaluation of Derivatives – The question requires evaluating the derivative at x = π/4, which involves knowing the values of sin(π/4) and cos(π/4).
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