The error is in Step 4.
The expression should be correctly broken down as follows:
From Step 4: \((4)(1) + (4)(3i) + (-2i)(1) + (-2i)(3i)\)
- \(4(1) = 4\)
- \(4(3i) = 12i\)
- \((-2i)(1) = -2i\)
- \((-2i)(3i) = -6i^2\) (and since \(i^2 = -1\), \(-6i^2\) becomes \(6\))
So the sum should be:
\[ 4 + 12i - 2i + 6 \]
Combining like terms gives:
\[ (4 + 6) + (12i - 2i) = 10 + 10i \]
Thus, the actual results are \(10 + 10i\), not \(10 + 14i\).
The specific error in Step 3 is the calculation of \(-612\) (the correct term should be \(6\)), and there is a mistake in combining the imaginary terms, leading to an error in identifying \(10i\) as \(14i\).
In summary:
- The error is with the imaginary addition and \(i^2\) treatment.
- The correct outcome should be \(10 + 10i\), not \(10 + 14i\).