Answer
$a_1=1 \\ a_2=-4 \\ a_3=9 \\ a_4=-16 \\ a_5=25$
Work Step by Step
We are given that $\{a_n\}=\left\{(-1)^{n+1}n^2\right\}$
In order to determine the first five terms, we will have to substitute $n=1,2,3,4,5$ into the given sequence {$a_n$}:
$$a_1=(-1)^{1+1} \times 1^2=(1)(1)=1 \\ a_2=(-1)^{2+1} \times 2^2=(-1)(4)=-4 \\ a_3=(-1)^{3+1} \times 3^2=(1)(9)=9 \\ a_4=(-1)^{4+1} \times 4^2=(-1)(16)=-16 \\ a_5=(-1)^{5+1} \times 5^2=(1)(25)=25$$
