Which of the following statements are true where ϕ(x) is a polynomial....
True Statements Regarding Roots of Polynomials
There are four statements given in the question related to the roots of a polynomial function ϕ(x). Let's analyze each statement one by one to determine which ones are true.
A. Between any two roots of ϕ(x)=0 lies at least one root of ϕ(x)γϕ(x)=0.
This statement is not true in general. For example, consider the polynomial ϕ(x) = x^2 - 1. It has two roots x = 1 and x = -1. However, the function ϕ(x)γϕ(x) = x^2 - 1 is positive for all x except x = 0. Therefore, there is no root of ϕ(x)γϕ(x) between x = 1 and x = -1.
B. Between any two roots of ϕ(x)=0 lies at least one root of xϕ(x)γϕ(x)=0.
This statement is true. Suppose ϕ(x) has two roots x1 and x2, where x1 < x2.="" then,="" by="" the="" intermediate="" value="" theorem,="" there="" exists="" a="" value="" c="" between="" x1="" and="" x2="" such="" that="" ϕ(c)="0." multiplying="" both="" sides="" of="" this="" equation="" by="" c,="" we="" get="" cϕ(c)="0." therefore,="" there="" exists="" a="" root="" of="" xϕ(x)γϕ(x)="" between="" x1="" and="" />
C. Between any two roots of ϕ(x)=0 lies at least one root of (x2+1)ϕ(x).
This statement is not true in general. For example, consider the polynomial ϕ(x) = x^2 - 1. It has two roots x = 1 and x = -1. However, the function (x^2+1)ϕ(x) is positive for all x. Therefore, there is no root of (x^2+1)ϕ(x) between x = 1 and x = -1.
D. Between any two roots of ϕ(x)=0 lies at least one root of ϕ'(x)xϕ(x)=0.
This statement is true. Suppose ϕ(x) has two roots x1 and x2, where x1 < x2.="" then,="" by="" rolle's="" theorem,="" there="" exists="" a="" value="" c="" between="" x1="" and="" x2="" such="" that="" ϕ'(c)="0." multiplying="" both="" sides="" of="" this="" equation="" by="" cϕ(c),="" we="" get="" ϕ'(c)cϕ(c)="0." therefore,="" there="" exists="" a="" root="" of="" ϕ'(x)xϕ(x)="" between="" x1="" and="" />
In summary, the true statements are:
- Between any two roots of ϕ(x)=0 lies at least one root of xϕ(x)γϕ(x)=0.
- Between any two roots of ϕ(x)=0 lies at least one root of ϕ'(x)xϕ(x)=0.
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