Applied Mathematics for Electrical Engineering (3130908)

BE | Semester-3   Winter-2019 | 26-11-2019

Q1) (a)

Find a real root of the equation x3-x-1=0 by using Regula - Falsi method correct to two decimal places.

Let, f(x) = x3-x-1
 
Now,
 
f(1) = (1)3 - 1 - 1 = -1 < 0
 
f(1.5) = (1.5)3 - 1.5 - 1 = 0.88 > 0
 
Therefore, root lies between [ 1, 1.5 ] .
 
Then, c = a - b - a f(b) - f(a)  f(a)
 
Then, c= 1-1.5 - 1 0.88 - (-1)  (-1)
 
Then, c= 1.27
 
 
a b f(a) < 0 f(b) > 0 c f(c)
1 1.5 - 1 0.88 1.27 - 0.24 < 0
1.27 1.5 - 0.24 0.88 1.32 - 0.02 < 0
1.32 1.5 - 0.02 0.88 1.32 ---
 
Therefore, x = 1.32 is the required root.