Why Does p+q Equal Zero in a Special Quadratic Equation?

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In the quadratic equation ax^2 + px + aq + q = 0, it is established that one root is always 1, which leads to the equation a + p + aq + q = 0 when x=1 is substituted. Since this holds true for any nonzero value of a, the equation simplifies to p + q = -a(1 + q). To satisfy this for all values of a, it must be that p + q = 0. This conclusion is drawn from the requirement that the equation remains valid regardless of the constant a. Thus, the proof that p + q equals zero is confirmed.
requal
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1. Consider the quadratic equation ax^2+px+aq+q=0 where a does not equal to zero & p and q are constants . It is known that one of the roots of the quadratic equation is always 1 regardless of the value of a. Prove that p+q=0

3. I have tried to factorize it and it became x(ax+p)+q(a+1)=0 but that's it. I kinda stuck /b]
 
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Hi Requal,
requal said:
1. Consider the quadratic equation ax^2+px+aq+q=0 where a does not equal to zero & p and q are constants . It is known that one of the roots of the quadratic equation is always 1 regardless of the value of a. Prove that p+q=0
That 1 is a root of the quadratic equation ax^2 + px + aq + q = 0 means that x=1 satisfies the equation; so plugging in x=1 we have a + p + aq + q = 0.
We are told this is true for any (nonzero) value of a. Can you take it from here?
 
Since ##px^9+q## is the factor, then ##x^9=\frac{-q}{p}## will be one of the roots. Let ##f(x)=27x^{18}+bx^9+70##, then: $$27\left(\frac{-q}{p}\right)^2+b\left(\frac{-q}{p}\right)+70=0$$ $$b=27 \frac{q}{p}+70 \frac{p}{q}$$ $$b=\frac{27q^2+70p^2}{pq}$$ From this expression, it looks like there is no greatest value of ##b## because increasing the value of ##p## and ##q## will also increase the value of ##b##. How to find the greatest value of ##b##? Thanks

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