Question 321266
{{{y^2 - 18y + 81 = 64}}} Start with the given equation.



{{{(y-9)^2=64}}} Factor the left side.



{{{x-9=""+-sqrt(64)}}} Take the square root of both sides.



{{{y-9=sqrt(64)}}} or {{{y-9=-sqrt(64)}}} Break up the "plus/minus" to form two equations.



{{{y-9=8}}} or {{{y-9=-8}}}  Take the square root of {{{64}}} to get {{{8}}}.



{{{y=9+8}}} or {{{y=9-8}}} Add {{{9}}} to both sides.



{{{y=17}}} or {{{y=1}}} Combine like terms.



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Answer:



So the solutions are {{{y=17}}} or {{{y=1}}}.