[tex]\bf x^2-\underline{b} x+b\implies \stackrel{given}{(x-2)}~(x-y)\impliedby \textit{now let's do some FOIL}\\\\
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\begin{cases}
-yx-2x=-\underline{b}x\implies y+2=\underline{b}\\
(-2)(-y)=b\implies 2y=b
\end{cases}
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\underline{b}=b\implies y+2=2y\implies 2=y[/tex]
what is b? from the first equation in the system, y + 2 = b.