## College Algebra (6th Edition)

First term(i = 1) $a_{1}$= (-2$\times$1 + 6) = -2 + 6 = 4 Second term(i = 2)$a_{2}$ = (- 2$\times$2 + 6) = -4 + 6 = 2 Third term(i = 3)$a_{3}$ = (-2$\times$3 + 6) = -6 + 6 = 0 Last term $a_{l}$(i = 40) = $a_{40}$ = (-2$\times$40 + 6) = -80 + 6 = -74 The sequence becomes = 4 + 2 + 0 +......+ (-74) Indicated Sum = 4 + 2 + 0 +......+ (-74) = -1400
First term(i = 1) $a_{1}$= (-2$\times$1 + 6) = -2 + 6 = 4 Second term(i = 2)$a_{2}$ = (- 2$\times$2 + 6) = -4 + 6 = 2 Third term(i = 3)$a_{3}$ = (-2$\times$3 + 6) = -6 + 6 = 0 Last term $a_{l}$(i = 40) = $a_{40}$ = (-2$\times$40 + 6) = -80 + 6 = -74 The sequence becomes = 4 + 2 + 0 +......+ (-74) Common difference (d)= 0 - 2 = 2 - 4 = -2 Number of terms (n) = 40 Indicated Sum = 4 + 2 + 0 +......+ (-74) = $\frac{n}{2}$(first term + last term) = $\frac{40}{2}$(4 + (-74) = $\frac{40}{2}$(-70) = 20$\times$ (-70) = - 1400