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📐 Mathematics  ·  Differential Equations  ·  JEE

The Fourier series of a periodic function uses:

Answer: Sinusoids and cosinusoids (trigonometric basis).

  • A Taylor polynomials expanded about a single fixed point
  • B Sinusoids and cosinusoids (trigonometric basis)
  • C Polynomial terms mainly, with few trigonometric components
  • D Real exponential terms mainly, with little oscillatory behavior

Correct answer: B. Sinusoids and cosinusoids (trigonometric basis)

Explanation: A periodic function f(x) with period 2L is expressed as f(x)=a₀/2+Σ[aₙcos(nπx/L)+bₙsin(nπx/L)]. Coefficients found by orthogonality of sin/cos. This is an infinite sum of harmonically related sinusoids and cosinusoids.

Family of Solution Curves: y = Ax²Each value of the constant A gives ONE particular curve from the family

The general solution y=Ax² represents an entire FAMILY of curves, one for each value of the arbitrary constant A; a particular solution (fixed by an initial condition) selects exactly one curve from this family.

Concept context

Equations involving derivatives and their solutions

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