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Engineering Mathematics
Numerical Methods
GATE 2012
Medium

The Newton-Raphson method is used to find the roots of the equation f(x)=x−cos(πx), 0≤x≤1. If the initial guess for the root is 0.5, then the value of x after the first iteration is

  • A1.02
  • B0.62
  • C0.55
  • 0.38

Explanation

f(x)=x−cos(πx), f'(x)=1+π sin(πx). At x0=0.5: f(0.5)=0.5−cos(π/2)=0.5−0=0.5; f'(0.5)=1+π sin(π/2)=1+π=4.1416. x1=x0−f(x0)/f'(x0)=0.5−0.5/4.1416≈0.5−0.1207=0.379≈0.38.

Source: GATE CH 2012 (2012)

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