<PRE><B>Question 473000</B>
f(x)=x^2-2x 



f(x+h)=(x+h)^2-2(x+h)



f(x+h)=x^2+2xh+h^2-2x-2h



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[f(x+h)-f(x)]/h



[(x^2+2xh+h^2-2x-2h)-(x^2-2x)]/h



[x^2+2xh+h^2-2x-2h-x^2+2x]/h



[2xh+h^2-2h]/h



[h(2x+h-2)]/h



2x+h-2



2x-2+h



So [f(x+h)-f(x)]/h = 2x-2+h when f(x)=x^2-2x</PRE>