SOLUTION: Explain why 3x^2+kx-1 is never {{{cross(positive)}}} {{{cross(definite)}}} <U>POSITIVELY DEFINED</U> for any value of k.

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Question 1185909: Explain why 3x^2+kx-1 is never POSITIVELY DEFINED for any value of k.

Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39617)   (Show Source): You can put this solution on YOUR website!

Answer by ikleyn(52781)   (Show Source): You can put this solution on YOUR website!
.

Consider the value of the given function at   x= 0:   it is  -1,  which is not positive.

It is true for any value of   " k ",   and it shows and proves that the given function
is never positively defined for any value of  " k ".

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Proved and explained.



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