Use Regular False method to determine where the smallest positive root is.
Choose two points a and b such that f(a) and f(b) are of opposite signs.
f(0)=1,f(1)=−3. With a=0 and b=1 find the (first) value of point of approximation:
x=x1=f(b)−f(a)af(b)−bf(a)=(−3)−10⋅(−3)−1⋅1=0.25. f(x1)=0.703.Therefore, the interval of unit length that contains the smallest positive root is [0;1].
Starting with this interval, find an interval of length 0.05 or less that contains the root, by Bisection method
Consider our interval [xL;xR]=[0;1]. Find the center of the interval and the value of the function at this point:
xc=2xL+xR=20+1=0.5, f(xc)=−0.125.
Check at what part of the interval - [xL;xC] or [xc;xR] - there is a root: if the values of the function at the ends of one of these intervals are opposite, there is a root:
f(0)f(0.5)<0,f(0.5)f(1)>0.Hence, we will only consider [0;0.5]. Perform the next iteration by bisection method:
xc=20+0.5=0.25,f(xc)=0.703.Is the root on the left or right of xc?f(0)f(0.25)>0,f(0.25)f(0.5)<0. Hence, we will only consider [0.25;0.5]. Perform the next iteration:
xc=20.25+0.5=0.375,f(xc)=0.35.Is the root on the left or right of xc?f(0.25)f(0.375)>0,f(0.375)f(0.5)<0.Hence, we will only consider [0.375;0.5]. Perform the next iteration:
xc=20.375+0.5=0.438,f(xc)=0.127.Is the root on the left of xc or on the right?f(0.438)f(0.375)>0,f(0.438)f(0.5)<0. Hence, we will only consider [0.438;0.5]. Perform the next iteration:
xc=20.438+0.5=0.469,f(xc)=0.0034.Is the root on the left of xc or on the right?f(0.438)f(0.469)>0,f(0.469)f(0.5)<0.But the length of both of these intervals is less than 0.05, therefore, the smallest positive root lies between 0.469 and 0.5.
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