Distribute to simplify the expression (3i + 4)(−2i − 5)

.(1 point)
+
i

1 answer

To simplify the expression \((3i + 4)(-2i - 5) + i\), we will first distribute the terms in the parentheses.

  1. Distribute \((3i + 4)\) and \((-2i - 5)\):

    \[ (3i + 4)(-2i) + (3i + 4)(-5) \]

    • For \((3i + 4)(-2i)\):

    \[ 3i \cdot (-2i) + 4 \cdot (-2i) = -6i^2 - 8i \]

    • For \((3i + 4)(-5)\):

    \[ 3i \cdot (-5) + 4 \cdot (-5) = -15i - 20 \]

  2. Now add these results together:

    \[ -6i^2 - 8i - 15i - 20 = -6i^2 - 23i - 20 \]

  3. Recall that \(i^2 = -1\):

    \[ -6(-1) - 23i - 20 = 6 - 23i - 20 \]

  4. Simplifying the constants:

    \[ 6 - 20 = -14 \]

Putting it all together, we have:

\[ -14 - 23i \]

  1. Finally, add \(i\):

    \[ -14 - 23i + i = -14 - 22i \]

Thus, the simplified expression is:

\[ \boxed{-14 - 22i} \]