$(5$ points$)$ In this problem, use the general expressions for left and right sums,

left$-$hand sum $=f(t_0)t+f(t_1)t+$cdots$+f(t_{n-1})t$

and

right$-$hand sum $=f(t_1)t+f(t_2)t+$cdots$+f(t_n)t,$

and the following table:

A$.$ If we use $n=4$ subdivisions, fill in the values:

$t=$

$t_0=,$;$t_1=,$;$t_2=,$;$t_3=,$;$t_4=$

$f(t_0)=,$;$f(t_1)=,$;$f(t_2)=,$;$f(t_3)=,$;$f(t_4)=$

B$.$ Find the left and right sums using $n=4$

left sum $=$

right sum $=$

c$.$ If we use $n=2$ subdivisions, fill in the values:

$t=$

$t_0=,$;$t_1=,$;$t_2=$

$f(t_0)=,$;$f(t_1)=,$;$f(t_2)=$

D$.$ Find the left and right sums using $n=2$

left sum $=$

right sum $=$