## Precalculus (6th Edition) Blitzer

To ﬁnd the first four terms of the sequence whose general term is $a_{n}$ = $(-1)^{n+1}$(n+4), we replace n in the formula with 1,2,3, and 4. n=1, $a_{1}$ = $(-1)^{1+1}$(1+4) = 1 * 5 = 5 n=2, $a_{2}$ = $(-1)^{2+1}$(2+4) = -1.*6 = -6 n=3, $a_{3}$ = $(-1)^{3+1}$(3+4) = 1 * 7 = 7 n=4,$a_{4}$ = $(-1)^{4+1}$(4+4) = -1 *8= -8 The ﬁrst four terms are 5,-6,7,-8.