Which of the following expresses the possible number of positive real solutions for the polynomial equation shown below?
2 answers:
In order to figure this out you need to use Descartes Rule. I attached a picture showing Descartes Rule. If the signs changes for when x is positive then the number of times it changes are the possible positive solution. If the sign changes when x is negative then the number of times it changes are the possible negative solutions. With that said the answer is A. View the picture I have attached for the possible + - and imaginary solutions.
Answer = A) One possible positive solution.
Answer = A) One possible positive solution.
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Given
we have
Squaring both sides, we have
And finally
Note that, when we square both sides, we have to assume that
because we're assuming that this fraction equals a square root, which is positive.
So, if that fraction is positive you'll actually have roots: choose
and you'll have
Which is a valid solution. If, instead, the fraction is negative, you'll have extraneous roots: choose
and you'll have
Squaring both sides (and here's the mistake!!) you'd have
which is not a solution for the equation, if we plug it in we have
Which is clearly false