Answer
Lower estimate = $-64$
Upper estimate = $16$
Work Step by Step
Lower estimate:
$L_5$ = $\Sigma_{i=1}^{5}f(x_{i-1})Δx$ = $4[f(10)+f(14)+f(18)+f(22)+f(26)]$ = $4[-12-6-2+1+3]$ = $-64$
Upper estimate:
$R_5$ = $\Sigma_{i=1}^{5}f(x_{i})Δx$ = $4[f(14)+f(18)+f(22)+f(26)+f(30)]$ = $4[-6-2+1+3+8]$ = $16$
