Answer
$a_1 = -4
\\a_2 = 5
\\a_3 = -6
\\a_4 = 7$
Work Step by Step
To find the first four terms of the given sequence, substitute 1, 2, 3, and 4 to $n$, respectively, then simplify.
$a_1 = (-1)^1(1+3) = -1(4) = -4
\\a_2 = (-1)^2(2+3) = 1(5) = 5
\\a_3 = (-1)^3(3+3) = -1(6) = -6
\\a_4 = (-1)^4(4+3) = 1(7) = 7$
