## Intermediate Algebra (6th Edition)

$-1, 4, -9, 16, -25$
Let's evaluate $a_1, a_2, a_3, a_4,$and $a_5$ by plugging in $1, 2, 3, 4,$ and $5$ for each $n$. We use PEMDAS (parentheses, exponentation, multiplication, division, addition, subtraction) to decide which operations go first. \begin{align} a_1 &amp;= (-1)^11^2 = -1\cdot1^2 = -1\cdot 1 = -1 \\ \\ a_2 &amp;= (-1)^22^2 = 1\cdot2^2 = 1 \cdot 4 = 4 \\ \\ a_3 &amp;= (-1)^33^2 = -1\cdot3^2 = -1\cdot 9 = -9 \\ \\ a_4 &amp;= (-1)^44^2 = 1\cdot4^2 = 1 \cdot 16 = 16 \\ \\ a_5 &amp;= (-1)^55^2 = -1\cdot5^2 = -1\cdot25 = -25 \\ \\ \end{align}