Question 146280

First count the sign changes of {{{f(x)=x^4-4x^3+6x^2-4x+1}}}


From {{{x^4}}} to {{{-4x^3}}}, there is a sign change from positive to negative 


From {{{-4x^3}}} to {{{6x^2}}}, there is a sign change from negative to positive 


From {{{6x^2}}} to {{{-4x}}}, there is a sign change from positive to negative 


From {{{-4x}}} to {{{1}}}, there is a sign change from negative to positive 


So there are 4 sign changes for the expression {{{f(x)=x^4-4x^3+6x^2-4x+1}}}. 


So there are 4, 2, or 0 positive zeros