Part a$)$ Use four approximating rectangles and right endpoints to estimate the area under $\backslash ($ f $\backslash ).($If necessary, round to four decimal places.$)$

$\backslash [$

R$\_\{4\}=$

$\backslash ]$

Part b$)$ Is your estimate from Part a$)$ an underestimate $($a$.$k$.$a$.$ lower estimate$)$ or an overestimate $($a$.$k$.$a$.$ upper estimate$)?$

$```$

lower estimate $($i$.$e$.$ underestimate$)$

upper estimate $($i$.$e$.$ overestimate$)$

$```$

Part c$)$ Now use four approximating rectangles and left endpoints to estimate the area under $\backslash ($ f $\backslash ).($If necessary, round to four decimal places.$)$

$\backslash [$

L$\_\{4\}=$

$\backslash ]$

Part d$)$ Is your estimate from Part c$)$ an underestimate $($a$.$k$.$a$.$ lower estimate$)$ or an overestimate $($a$.$k$.$a$.$ upper estimate$)?$

lower estimate $($i$.$e$.$ underestimate$)$

upper estimate $($i$.$e$.$ overestimate$)$