Question 1063900
{{{f(a)=-a^3}}}
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{{{f(a+h)=-(a+h)^3=-a^3-3ha^2-3h^2a-h^3}}}
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{{{f(a+h)-f(a)=-a^3-3ha^2-3h^2a-h^3-(-a^3)}}}
{{{f(a+h)-f(a)=-ha^2-3h^2a-h^3}}}

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{{{(f(a+h)-f(a))/h=(-ha^2-3h^2a-h^3)/h}}}
{{{(f(a+h)-f(a))/h=-a^2-3ha-h^2}}}