Let $I={\displaystyle \underset{0}{\overset{4}{}}}f(x)dx,$ where $f$ is the function whose graph is shown.

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$($a$)$ Use the graph to find $L_2,R_2$ and $M_2.$

$L_2=$

$R_2=56$

$M_2=$

$($b$)$ Are these underestimates or overestimates of I $?$

$L_2$ is an underestimate.

$L_2$ is an overestimate.

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