1. Express $z$ in terms of $\overline{w}$ from the second equation
(4−i)w=z−3i
z=(4−i)w+3i
2. Substitute the expression for $z$ into the first equation and simplify
2i[(4−i)w+3i]+w=5+7i
(8i−2i2)w+6i2+w=5+7i
(2+8i)w−6+w=5+7i
w+(2+8i)w=11+7i
3. Substitute $w = a + bi$ into the simplified equation and expand
Let w=a+bi and its conjugate w=a−bi, where a,b∈R.
(a+bi)+(2+8i)(a−bi)=11+7i
a+bi+2a−2bi+8ai−8bi2=11+7i
a+bi+2a−2bi+8ai+8b=11+7i
(3a+8b)+(8a−b)i=11+7i
4. Equate the real and imaginary parts to form a system of linear equations
Comparing the real and imaginary parts:
3a+8b=11— (1)
8a−b=7— (2)
5. Solve the system of equations to find $w$
From (2), we get b=8a−7.
Substitute into (1):
3a+8(8a−7)=11
3a+64a−56=11
67a=67
a=1
Substitute a=1 back into the expression for b:
b=8(1)−7=1
Therefore, w=1+i.
6. Substitute $\overline{w}$ back into the expression for $z$ to solve for $z$
z=(4−i)(1−i)+3i
z=4−4i−i+i2+3i
z=4−5i−1+3i
z=3−2i
答案z=3−2i, w=1+i