Hi, this is my first post here! I've been looking at some past examples to determine the stationary points of f(x), but keep coming into errors wherever I look. 'm' is saved so shouldn't cause any issues, I just cant get past the issues with 'x' The equation is : f(x) = (5*x^2)/(m(x^2+1)) Initially I tried: >> f=(5*x^2)/(m(x^2+1)) Undefined function or variable 'x'. Followed by (purely guessing to see if I could get it to work: >> syms x >> f=(5*x^2)/(m(x^2+1)) Error using sym/subsindex (line 766) Invalid indexing or function definition. When defining a function, ensure that the arguments are symbolic variables and the body of the function is a SYM expression. When indexing, the input must be numeric, logical, or ':'. I seem unable to get past this, and any help would greatly be appreciated

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12/20/2016 1:08:03 PM

On 12/20/2016 7:08 AM, Lmore wrote: > Hi, this is my first post here! > I've been looking at some past examples to determine the stationary points of f(x), >but keep coming into errors wherever I look. 'm' is >saved so shouldn't cause any issues, I just cant get past the issues with 'x' > > The equation is : f(x) = (5*x^2)/(m(x^2+1)) > > Initially I tried: >>> f=(5*x^2)/(m(x^2+1)) > Undefined function or variable 'x'. > > Followed by (purely guessing to see if I could get it to work: >>> syms x >>> f=(5*x^2)/(m(x^2+1)) > Error using sym/subsindex (line 766) > Invalid indexing or function definition. When defining a function, >ensure that the arguments are symbolic variables and the body > of the function is a SYM expression. When indexing, the input must >be numeric, logical, or ':'. > > > I seem unable to get past this, and any help would greatly be appreciated > One way might be clear syms x m f=(5*x^2)/(m*(x^2+1)); df=diff((5*x^2)/(m*(x^2+1)),x) (10*x)/(m*(x^2 + 1)) - (10*x^3)/(m*(x^2 + 1)^2) solve(df==0,x) 0

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12/20/2016 9:00:35 PM