EXERCISE 9 (b)
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1. In each of the following find r+s, r-s, rs,
"ifr denotes the first complex number and
denotes the second complex number:
(1) 3+ 71,1 (ii) -1, 5+2i
(iii) 3i, 1- (iv) -7, -1 -3i
(v) 7 +3i, 3i-1
2. Solve each of the following
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Answers
Given : pair of complex number
(1) 3+ 7i,1
7 +3i, 3i-1
To Find : r + s , r - s and rs where r is 1st complex number and s is 2nd .
Solution:
(1) 3+ 7i,1
r = 3 + 7i
s = 1
r + s = ( 3 + 7i ) + 1
= ( 3 + 1) + 7i
= 4 + 7i
r - s = ( 3 + 7i ) - 1
= ( 3 - 1) + 7i
= 2 + 7i
rs = ( 3 + 7i ) * 1 = 3 + 7i
7 +3i, 3i-1
r = 7 + 3 i
s = 3i - 1 = - 1 + 3i
r + s = 10 + 6i
r -s = 8
rs = (7 +3i) (-1 +3i) = -7 + 18i + 9i²
i² = - 1
= -16 + 18 i
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Answer:
actually question is wrong
Step-by-step explanation:
1) 3+7i , i
r+s = 3+7i + i = 3+8i
r-s = 3+7i - i = 3+6i
rs = 3 + 7i * i = 3i-7
r/s = 3+ 7i / i = 7-3