Here's the solution to the problems.
: Express j(4−j5)2+j3+j2 in the form a+jb.
Step 1: Simplify the denominator of the first term and the second term.
For the first term's denominator:
j(4−j5)=j4−j25=j4−(−1)5=5+j4
For the second term:
j2=j2×−j−j=−j2−j2=−(−1)−j2=1−j2=−j2
Step 2: Simplify the first term, 5+j42+j3, by multiplying the numerator and denominator by the conjugate of the denominator, which is 5−j4.
5+j42+j3=5+j42+j3×5−j45−j4
Numerator:
(2+j3)(5−j4)=2(5)+2(−j4)+j3(5)+j3(−j4)
=10−j8+j15−j212
=10+j7−(−1)12
=10+j7+12=22+j7
Denominator:
(5+j4)(5−j4)=52−(j4)2
=25−j216
=25−(−1)16
=25+16=41
So the first term simplifies to 4122+j7=4122+j417.
Step 3: Add the simplified first term and the simplified second term.
(4122+j417)+(−j2)
=4122+j417−j4182
=4122+j(417−82)
=4122−j4175
The expression in the form a+jb is 4122−j4175.
: If z=2+j31+1−j21, express z in the form a+jb.
Step 1: Simplify the first term, 2+j31, by multiplying the numerator and denominator by its conjugate, 2−j3.
2+j31=2+j31×2−j32−j3
=22−(j3)22−j3=4−j292−j3=4−(−1)92−j3=4+92−j3=132−j3=132−j133
Step 2: Simplify the second term, 1−j21, by multiplying the numerator and denominator by its conjugate, 1+j2.
1−j21=1−j21×1+j21+j2
=12−(j2)21+j2=1−j241+j2=1−(−1)41+j2=1+41+j2=51+j2=51+j52
Step 3: Add the simplified first and second terms.
z=(132−j133)+(51+j52)
Combine the real parts and the imaginary parts:
z=(132+51)+j(−133+52)
Find a common denominator for the real parts (13 and 5, LCM is 65):
132+51=13×52×5+5×131×13=6510+6513=6523
Find a common denominator for the imaginary parts (13 and 5, LCM is 65):
−133+52=13×5−3×5+5×132×13=65−15+6526=6511
So, z=6523+j6511.
The expression for z in the form a+jb is 6523+j6511.
That's 2 down. 3 left today — send the next one.