Find all roots of the polynomial equation

Jasmine Todd

Jasmine Todd

Answered question

2022-04-03

Find all roots of the polynomial equation p(p(x))x=0.
Let p(x) be a quadratic polynomial such that for distinct reals α and β,
p(α)=α & p(β)=β
Show that α and β are the roots of the following equation
p(p(x))x=0

Answer & Explanation

arrebusnaavbz

arrebusnaavbz

Beginner2022-04-04Added 18 answers

Write q(x)=p(x)x, then given equation is equivalent to
q(q(x)+x)+q(x)=0
Since α and β are roots for q we have
q(x)=c(xα)(xβ)
where c0, so
c(q(x)+xα)(q(x)+xβ)+c(xα)(xβ)=0
so (xα)(xβ)((cxcα+1)(cxcβ+1)+1)=0
Need to solve the red equation...

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