- #1
riddle
- 38
- 0
Homework Statement
Show that a root of the equation x3 - 3x - 5 =0 lies in the interval [2,3], and then find the root using linear interpolation correct to one decimal place.
Homework Equations
n/a
The Attempt at a Solution
This is my first ever time using interpolants ( well at least in the sense of solving a polynomial. I think I've used them before... but instinctively.)
This is what I did:
3 [tex]\div[/tex] 13 = (x1 - 2) [tex]\div[/tex] (3-x1)
to end up with x1 = 2.1875.
I went on to get the third approximation only to find out that it was outside the range (less than 2).
I checked what the solution said, and it said:
3 [tex]\div[/tex] 13 = (3-x1) [tex]\div[/tex] (x1 - 2)
I'm utterly confused. Please help.