Solve Function not working properly

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Chris Ariante
Chris Ariante on 22 Feb 2013
Hello I am new to matlab and am having a lot of difficulty solving a simple algebraic equation. I want to solve:
X^3-6X^2+18=0 for X which should be the value 2 however matlab is providing me with a very different answer. The code i am typing is:
solve(x.^3-6*X.^2+18,X)
and the answer is as follows:
ans=
-2.941250671603633621189774
1.230510698487091567868454 - 2.588291611086283205444294848*i
and continues to repeat with similar integers for a number of lines.
Any help is appreciated. Thanks!

Answers (2)

Azzi Abdelmalek
Azzi Abdelmalek on 22 Feb 2013
Edited: Azzi Abdelmalek on 22 Feb 2013
syms x
sol=solve(x.^3-6*x.^2+18)
sol=subs(sol)

Walter Roberson
Walter Roberson on 22 Feb 2013
2 is not the solution for that, even if we read "6X^2" as possibly meaning (6X)^2. 2 is, however, a solution for
x^3-6*x^2+16

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