The quadratic equation for an equation with double roots 9 is : [tex]x^{2}[/tex]-18x+81 = 0.
what is a Quadratic equation?
A quadratic equation is an Algebraic equation with the highest power of its variable as 2.
It can be solved by several methods : Factorization, completing the square and graphical methods.
Analysis
if 9 is the double root of the equation, it means x = 9 or x = 9
So (x-9)(x-9) are factors
Therefore,
(x-9)(x-9) = 0
[tex]x^{2}[/tex] - 9x-9x + 81 = 0
[tex]x^{2}[/tex] -18x+81 = 0
in conclusion, the quadratic equation of the double root 9 is: [tex]x^{2}[/tex] -18x+81 = 0
Learn more about Quadratic equations : brainly.com/question/1214333
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