Final answer:
The subtraction of Q from P is (5 - 21i) - (-3 + 7i), which simplifies to 8 - 28i. So, the answer is option B: 2 - 28i.
Step-by-step explanation:
To find the expression for P - Q, we subtract complex number Q from P. Given numbers are P = (5 - 21i) and Q = (-3 + 7i).
The subtraction of Q from P is performed as follows:
P - Q = (5 - 21i) - (-3 + 7i)
= 5 - 21i + 3 - 7i (Subtracting -3 turns to adding +3, and subtracting +7i turns to adding -7i)
= 5 + 3 - 21i - 7i
= 8 - 28i (Combine like terms)
Thus, the expression in the form a + bi is 8 - 28i, which corresponds to option B.