05 Complex Numbers and Quadratic Equations
Exercise 01
Question:
Find the multiplicative inverse of the complex number −i
Answer:
Answer: Step 1: The multiplicative inverse of any number is the reciprocal of the number.
Step 2: The reciprocal of -i is 1/-i.
Step 3: Therefore, the multiplicative inverse of -i is 1/-i.
Question:
Express the given complex number in the form a+ib:(1−i)4
Answer:
(1-i)^4 = (1-i)(1-i)(1-i)(1-i) = (1-i)(1-i)(1-i-i) = (1-i)(1-2i) = (1-2i-i^2) = (1-2i-1) = 1-2i-1+i^2 = 1-2i-1+(-1) = 1-2i-2 = 1-2(i+1) = 1-2i-2i = 1-4i = a+ib = 1-4i
Therefore, the complex number in the form a+ib is 1-4i.
Question:
Find the multiplicative inverse of the complex number √5+3i.
Answer:
Answer: Step 1: Find the conjugate of the complex number √5+3i. Conjugate = √5-3i
Step 2: Find the modulus of the complex number √5+3i. Modulus = |√5+3i| = √(5^2 + 3^2) = √34
Step 3: Find the multiplicative inverse of the complex number √5+3i. Multiplicative inverse = (√5-3i)/√34
Question:
(5i)(−3/5i)
Answer:
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First, combine the two terms by adding them: 5i + (-3/5i)
-
Simplify the terms by multiplying the numerator and denominator of the second term by the complex conjugate of the denominator of the second term: 5i + (-3/(5i)(-5i)) = 5i + (15/25)
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Simplify the terms by combining the coefficients of the terms: 5i + 15/25 = (5i + 15)/25
-
Simplify the terms by multiplying the numerator and denominator by the reciprocal of the denominator: (5i + 15)/25 * 25/25 = (5i + 15)/25 * 1 = (5i + 15)
Question:
Solve : i9+i19
Answer:
Step 1: Rewrite the expression using the power of a power rule.
i^9 + i^19 = i^(9+19)
Step 2: Calculate the value of i^(9+19).
i^(9+19) = i^28
Question:
Express the given complex number 3(7+i7)+i(7+i7) in the form a+ib,
Answer:
Given: 3(7+i7)+i(7+i7)
Step 1: 3(7+i7) = 21 + 3i7
Step 2: i(7+i7) = -7 + i7
Step 3: 21 + 3i7 + (-7 + i7)
Step 4: 21 - 7 + 4i7
Answer: 21 - 7 + 4i7 = 14 + 4i7
Question:
Express the given complex number in the form a+ib: (−2−1/3i)3
Answer:
Given complex number, z = (-2 - i/3)
Step 1: Calculate z^3
z^3 = (-2 - i/3)^3
Step 2: Expand the expression
(-2 - i/3)^3 = -8 - 8i/3 - 2i^2/3 - (i/3)^3
Step 3: Simplify the expression
-8 - 8i/3 - 2i^2/3 - (i/3)^3 = -8 - 8i/3 - 2i^2/3 - i/27
Step 4: Express in the form a+ib
-8 - 8i/3 - 2i^2/3 - i/27 = -8 - 8i/3 - 2i^2/3 - i/27 = -8 - 8i/3 - 2i - i/9 = -8 - 10i - i/9
Therefore, the given complex number in the form a+ib is: -8 - 10i - i/9
Question:
Express the following expression in the form of a+ib ; (3+i√5)(3−i√5)/(√3+√2i)−(√3−i√2)
Answer:
Given, (3+i√5)(3−i√5)/(√3+√2i)−(√3−i√2)
Step 1: Multiply the numerator and denominator by the conjugate of the denominator.
(3+i√5)(3−i√5)(√3-√2i)/((√3+√2i)(√3-√2i))-((√3−i√2)(√3-√2i))
Step 2: Simplify the numerator and denominator.
(3+i√5)(3−i√5)(3+√2i)/(9+2i√6)-(3+√2i)(3+√2i)
Step 3: Simplify the numerator and denominator further.
(9-5√5)/(9+2i√6)-9
Step 4: Simplify the expression further.
-14-2i√6/9+2i√6
Step 5: Express the expression in the form of a+ib.
-14/9+2i√6/9
Question:
Solve: [(1/3+i7/3)+(4+i1/3)]−(−4/3+i)
Answer:
Step 1: Combine like terms on the left side of the equation: [(1/3+i7/3)+(4+i1/3)]−(−4/3+i)
Step 2: [(5/3+i8/3)]−(−4/3+i)
Step 3: [5/3+i8/3 + 4/3-i]
Step 4: 9/3+i7/3
Question:
Express (31+3i)3 in the form a+ib. A 343/34+23i B −343/34−23i C 242/27+26i D −242/27−26i
Answer:
Answer: C 242/27+26i
Question:
Find the modulus and amplitude of 4+3i.
Answer:
Answer: Modulus: 5 Amplitude: 5
Question:
Express (1−i)−(1+i6) as a+ib
Answer:
(1−i)−(1+i6) = (1−i) − 1 - i6 = -i - 1 - i6 = -i - 1 - (i/6) = -i - 1 - (1/6)i = -i - 1 + (-1/6)i = -i - 1 + (1/6)i = (-1 - 1 + (1/6))i = (-2 + (1/6))i = (-2 + (1/6))(1 + i) = (-2 + (1/6)) + (-2 + (1/6))i = (-2 + (1/6)) + i(-2 + (1/6)) = a + ib = (-2 + (1/6)) + i(-2 + (1/6)) = (-2 + (1/6)) + i(-2 + (1/6))
Question:
Solve the problem:- (1/5+i2/5)−(4+i5/2)
Answer:
Given, (1/5 + i2/5) - (4+i5/2)
Step 1: Rewrite the given expression as,
(1/5 + i2/5) - (4+ i5/2) = (1/5 - 4) + (i2/5 - i5/2)
Step 2: Simplify the expression,
(1/5 - 4) + (i2/5 - i5/2) = -3.8 + (-3.5i)
Hence, the solution is -3.8 + (-3.5i).
Question:
Evaluate i−39.
Answer:
i^−39 = 1/i^39
= 1/(i^2)^19
= 1/i^38
= 1/i^2 * 1/i^36
= 1/i^2 * (1/i^18)^2
= 1/i^2 * (1/i^2)^18
= (1/i^2)^19
JEE NCERT Solutions (Mathematics)
01 Sets
02 Relations and Functions
03 Trigonometric Functions
04 Principle of Mathematical Induction
05 Complex Numbers and Quadratic Equations
06 Linear Inequalities
07 Permutations and Combinations
08 Binomial Theorem
09 Sequences and Series
10 Straight Lines Exercise
10 Straight Lines Miscellaneous
11 Conic Sections
12 Introduction to Three Dimensional Geometry
13 Limits and Derivatives
14 Mathematical Reasoning
15 Statistics
16 Probability