Question #$2($a$)$: Recall that $x_1$ is the value of $x$ at which we would like to compute the instantaneous rate of change. What value should we use for $x_1?$

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Question #$2($b$)$: Simplify the expression $f(x_1+h)-f(x_1)$ using the value of $x_1$ from Question #$2($a$).$ You may use the fact that $(a+b{)}^3=a^3+3*a^2*b+3*a*b^2+b^3$