Answer
$14-18i$
Work Step by Step
We multiply the two complex numbers using the FOIL method:
Step 1: $wz$
Step 2: $(2-4i)(5+i)$
Step 3: $2(5+i)-4i(5+i)$
Step 4: $10+2i-20i-4i^{2}$
Step 5: $10-18i-4i^{2}$
Since $i^{2}=-1$, we substitute the value of $i^{2}$ in the expression and simplify:
Step 6: $10-18i-4(-1)$
Step 7: $10-18i+4$
Step 8: $14-18i$
The answer is in rectangular form.
