[tex]\bf \textit{difference of squares}
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(a-b)(a+b) = a^2-b^2\qquad \qquad
a^2-b^2 = (a-b)(a+b)\\\\
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[tex]\bf f(x)=\cfrac{x^2-1}{x-1}\implies f(x)=\cfrac{x^2-1^2}{x-1}\implies f(x)=\cfrac{(\underline{x-1})(x+1)}{\underline{x-1}}
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f(x)=x+1\qquad \qquad \qquad \qquad \qquad g(x)=x+1\\\\
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\textit{they're, kinda, except that, when x = 1}
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g(x)=(1)+1\implies g(x)=2
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f(x)=\cfrac{(1)^2-1}{(1)-1}\implies f(x)=\cfrac{0}{0}\impliedby und efined[/tex]