Chapters
Chapter 2: Relations and Functions
Chapter 3: Trigonometric Functions
Chapter 4: Principle of Mathematical Induction
Chapter 5: Complex Numbers and Quadratic Equations
Chapter 6: Linear Inequalities
Chapter 7: Permutations and Combinations
Chapter 8: Binomial Theorem
Chapter 9: Sequences and Series
Chapter 10: Straight Lines
Chapter 11: Conic Sections
Chapter 12: Introduction to Three Dimensional Geometry
Chapter 13: Limits and Derivatives
Chapter 14: Mathematical Reasoning
Chapter 15: Statistics
Chapter 16: Probability
Chapter 5: Complex Numbers and Quadratic Equations
NCERT solutions for Mathematics Exemplar Class 11 Chapter 5 Complex Numbers and Quadratic EquationsSolved Examples [Pages 78 - 90]
Evaluate: (1 + i)6 + (1 – i)3
If `(x + iy)^(1/3)` = a + ib, where x, y, a, b ∈ R, show that `x/a - y/b` = – 2(a2 + b2)
Solve the equation `z^2 = barz`, where z = x + iy
If the imaginary part of `(2z + 1)/(iz + 1)` is – 2, then show that the locus of the point representing z in the argand plane is a straight line.
If |z2 – 1| = |z|2 + 1, then show that z lies on imaginary axis.
Let z1 and z2 be two complex numbers such that `barz_1 + ibarz_2` = 0 and arg (z1 z2) = π. Then find arg (z1).
Let z1 and z2 be two complex numbers such that |z1 + z2| = |z1| + |z2|. Then show that arg (z1) – arg (z2) = 0.
If z1, z2, z3 are complex numbers such that `|z_1| = |z_2| = |z_3| = |1/z_1 + 1/z_2 + 1/z_3|` = 1, then find the value of |z1 + z2 + z3|.
If a complex number z lies in the interior or on the boundary of a circle of radius 3 units and centre (– 4, 0), find the greatest and least values of |z + 1|
Locate the points for which 3 < |z| < 4
Find the value of 2x4 + 5x3 + 7x2 – x + 41, when x = `-2 - sqrt(3)"i"`.
Find the value of P such that the difference of the roots of the equation x2 – Px + 8 = 0 is 2.
Find the value of a such that the sum of the squares of the roots of the equation x2 – (a – 2)x – (a + 1) = 0 is least
Find the value of k if for the complex numbers z1 and z2, `|1 - barz_1z_2|^2 - |z_1 - z_2|^2 = k(1 - |z_1|^2)(1 - |"z"_2|^2)`
If z1 and z2 both satisfy `"z" + bar"z" = 2|"z" - 1|` arg `("z"_1 - "z"_2) = pi/4`, then find `"Im" ("z"_1 + "z"_2)`.
Fill in the blanks:
The real value of ‘a’ for which 3i3 – 2ai2 + (1 – a)i + 5 is real is ______.
If |z| = 2 and arg (z) = `pi/4`, then z = ______.
The locus of z satisfying arg (z) = `pi/3` is ______.
The value of `(- sqrt(-1))^(4"n" - 3)`, where n ∈ N, is ______.
The conjugate of the complex number `(1 - i)/(1 + i)` is ______.
If a complex number lies in the third quadrant, then its conjugate lies in the ______.
If (2 + i)(2 + 2i)(2 + 3i) ... (2 + ni) = x + iy, then 5.8.13 ... (4 + n2) = ______.
State true or false for the following:
Multiplication of a non-zero complex number by i rotates it through a right angle in the anti-clockwise direction.
True
False
The complex number cosθ + i sinθ can be zero for some θ.
True
False
If a complex number coincides with its conjugate, then the number must lie on imaginary axis.
True
False
The argument of the complex number z = `(1 + i sqrt(3))(1 + i)(cos theta + i sin theta)` is `(7pi)/12 + theta`.
True
False
The points representing the complex number z for which |z + 1| < |z − 1| lies in the interior of a circle.
True
False
If three complex numbers z1, z2 and z3 are in A.P., then they lie on a circle in the complex plane.
True
False
If n is a positive integer, then the value of in + (i)n+1 + (i)n+2 + (i)n+3 is 0.
True
False
Match the statements of column A and B.
| Column A | Column B |
| (a) The value of 1+ i2 + i4 + i6 + ... i20 is | (i) purely imaginary complex number |
| (b) The value of `i^(-1097)` is | (ii) purely real complex number |
| (c) Conjugate of 1 + i lies in | (iii) second quadrant |
| (d) `(1 + 2i)/(1 - i)` lies in | (iv) Fourth quadrant |
| (e) If a, b, c ∈ R and b2 – 4ac < 0, then the roots of the equation ax2 + bx + c = 0 are non real (complex) and |
(v) may not occur in conjugate pairs |
| (f) If a, b, c ∈ R and b2 – 4ac > 0, and b2 – 4ac is a perfect square, then the roots of the equation ax2 + bx + c = 0 |
(vi) may occur in conjugate pairs |
What is the value of `(i^(4n + 1) -i^(4n - 1))/2`?
What is the smallest positive integer n, for which (1 + i)2n = (1 – i)2n?
What is the reciprocal of `3 + sqrt(7)i`
If z1 = `sqrt(3) + i sqrt(3)` and z2 = `sqrt(3) + i`, then find the quadrant in which `(z_1/z_2)` lies.
What is the conjugate of `(sqrt(5 + 12i) + sqrt(5 - 12i))/(sqrt(5 + 12i) - sqrt(5 - 12i))`?
What is the principal value of amplitude of 1 – i?
What is the polar form of the complex number (i25)3?
What is the locus of z, if amplitude of z – 2 – 3i is `pi/4`?
If 1 – i, is a root of the equation x2 + ax + b = 0, where a, b ∈ R, then find the values of a and b.
Objective Type Questions from 28 to 33
1 + i2 + i4 + i6 + ... + i2n is ______.
Positive
Negative
0
Can not be evaluated
If the complex number z = x + iy satisfies the condition |z + 1| = 1, then z lies on ______.
X-axis
Circle with centre (1, 0) and radius 1
Circle with centre (–1, 0) and radius 1
Y-axis
The area of the triangle on the complex plane formed by the complex numbers z, – iz and z + iz is ______.
|z|2
`|barz|^2`
`|z|^2/2`
None of these
The equation |z + 1 – i| = |z – 1 + i| represents a ______.
Straight line
Circle
Parabola
Hyperbola
Number of solutions of the equation z2 + |z|2 = 0 is ______.
1
2
3
Infinitely many
The amplitude of `sin pi/5 + i(1 - cos pi/5)` is ______.
`(2pi)/5`
`pi/5`
`pi/15`
`pi/10`
NCERT solutions for Mathematics Exemplar Class 11 Chapter 5 Complex Numbers and Quadratic EquationsExercise [Pages 91 - 97]
Short Answer
For a positive integer n, find the value of `(1 - i)^n (1 - 1/i)^"n"`
Evaluate `sum_(n = 1)^13 (i^n + 1^(n + 1))`, where n ∈ N.
If `((1 + i)/(1 - i))^3 - ((1 - i)/(1 + i))^3` = x + iy, then find (x, y).
If `(1 + i)^2/(2 - i)` = x + iy, then find the value of x + y.
If `((1 - i)/(1 + i))^100` = a + ib, then find (a, b).
If a = cos θ + i sin θ, find the value of `(1 + "a")/(1 - "a")`.
If (1 + i)z = `(1 - i)barz`, then show that z = `-ibarz`.
If z = x + iy , then show that `z barz + 2(z + barz) + b` = 0, where b ∈ R, represents a circle.
If the real part of `(barz + 2)/(barz - 1)` is 4, then show that the locus of the point representing z in the complex plane is a circle.
Show that the complex number z, satisfying the condition arg `((z - 1)/(z + 1)) = pi/4` lies on a circle.
Solve the equation |z| = z + 1 + 2i.
Long Answer
If |z +1| = z + 2(1 + i), then find z.
If arg (z – 1) = arg (z + 3i), then find x – 1: y. where z = x + iy.
Show that `|(z - 2)/(z - 3)|` = 2 represents a circle. Find its centre and radius.
If `(z - 1)/(z + 1)` is purely imaginary number (z ≠ – 1), then find the value of |z|.
z1 and z2 are two complex numbers such that |z1| = |z2| and arg (z1) + arg (z2) = π, then show that z1 = `-barz_2`.
If |z1| = 1(z1 ≠ –1) and z2 = `(z_1 - 1)/(z_1 + 1)`, then show that the real part of z2 is zero.
If z1, z2 and z3, z4 are two pairs of conjugate complex numbers, then find arg `(z_1/z_4)` + arg `(z_2/z_3)`.
If |z1| = |z2| = ... = |zn| = 1, then show that |z1 + z2 + z3 + ... + zn| = `|1/z_1 + 1/z_2 + 1/z_3 + ... + 1/z_n|`.
If for complex numbers z1 and z2, arg (z1) – arg (z2) = 0, then show that `|z_1 - z_2| = |z_1| - |z_2|`
Solve the system of equations Re(z2) = 0, z = 2.
Find the complex number satisfying the equation `z + sqrt(2) |(z + 1)| + i` = 0.
Write the complex number z = `(1 - i)/(cos pi/3 + i sin pi/3)` in polar form.
If z and w are two complex numbers such that |zw| =1 and arg (z) – arg (w) = `pi/2`, then show that `barz`w = – i.
Fill in the blanks of the following:
For any two complex numbers z1, z2 and any real numbers a, b, |az1 – bz2|2 + |bz1 + az2|2 = ______.
The value of `sqrt(-25) xx sqrt(-9)` is ______.
The number `(1 - i)^3/(1 - i^2)` is equal to ______.
The sum of the series i + i2 + i3 + ... upto 1000 terms is ______.
Multiplicative inverse of 1 + i is ______.
If z1 and z2 are complex numbers such that z1 + z2 is a real number, then z2 = ______.
arg (z) + arg `barz (barz ≠ 0)` is ______.
If |z + 4| ≤ 3, then the greatest and least values of |z +1| are ______ and ______.
If `|(z - 2)/(z + 2)| = pi/6`, then the locus of z is ______.
If |z| = 4 and arg (z) = `(5pi)/6`, then z = ______.
State whether the following is True or False:
The order relation is defined on the set of complex numbers.
True
False
Multiplication of a non-zero complex number by – i rotates the point about origin through a right angle in the anti-clockwise direction.
True
False
For any complex number z the minimum value of |z + |z – 1| is 1.
True
False
The locus represented by |z – 1| = |z – i| is a line perpendicular to the join of (1, 0) and (0, 1).
True
False
If z is a complex number such that z ≠ 0 and Re (z) = 0, then Im (z2) = 0.
True
False
The inequality |z – 4| < |z – 2| represents the region given by x > 3.
True
False
Let z1 and z2 be two complex numbers such that |z1 + z2| = |z1| + |z2|, then arg (z1 – z2) = 0.
True
False
2 is not a complex number.
True
False
Match the statements of Column A and Column B.
| Column A | Column B |
| (a) The polar form of `i + sqrt(3)` is | (i) Perpendicular bisector of segment joining (– 2, 0) and (2, 0) |
| (b) The amplitude of `-1 + sqrt(-3)` is | (ii) On or outside the circle having centre at (0, – 4) and radius 3. |
| (c) If |z + 2| = |z − 2|, then locus of z is | (iii) `(2pi)/3` |
| (d) If |z + 2i| = |z − 2i|, then locus of z is | (iv) Perpendicular bisector of segment joining (0, – 2) and (0, 2). |
| (e) Region represented by |z + 4i| ≥ 3 is | (v) `2(cos pi/6 + i sin pi/6)` |
| (f) Region represented by |z + 4i| ≤ 3 is | (vi) On or inside the circle having centre (– 4, 0) and radius 3 units. |
| (g) Conjugate of `(1 + 2i)/(1 - i)` lies in | (vii) First quadrant |
| (h) Reciprocal of 1 – i lies in | (viii) Third quadrant |
What is the conjugate of `(2 - i)/(1 - 2i)^2`?
If |z1| = |z2| = , is it necessary that z1 = z2?
If `(a^2 + 1)^2/(2a - i)` = x + iy, what is the value of x2 + y2?
Find z if |z| = 4 and arg (z) = `(5pi)/6`.
Find `|(1 + i) ((2 + i))/((3 + i))|`.
Find principal argument of `(1 + i sqrt(3))^2`.
Where does z lie, if `|(z - 5i)/(z + 5i)|` = 1.
Objective Type Questions from 35 to 50
sinx + i cos 2x and cos x – i sin 2x are conjugate to each other for ______.
x = nπ
x = `(n + 1/2) pi/2`
x = 0
No value of x
The real value of α for which the expression `(1 - i sin alpha)/(1 + 2i sin alpha)` is purely real is ______.
`(n + 1) pi/2`
`(2n + 1) pi/2`
nπ
None of these, where n ∈N
If z = x + iy lies in the third quadrant, then `barz/z` also lies in the third quadrant if ______.
x > y > 0
x < y < 0
y < x < 0
y > x > 0
The value of `(z + 3)(barz + 3)` is equivalent to ______.
|z + 3|2
|z – 3|
z2 + 3
None of these
If `((1 + i)/(1 - i))^x` = 1, then ______.
x = 2n + 1
x = 4n
x = 2n
x = 4n + 1, where n ∈ N
A real value of x satisfies the equation `((3 - 4ix)/(3 + 4ix))` = α − iβ (α, β ∈ R) if α2 + β2 = ______.
1
– 1
2
– 2
Which of the following is correct for any two complex numbers z1 and z2?
|z1z2| = |z1|z2|
arg (z1z2) = arg (z1) . arg (z2)
|z1 + z2| = |z1| + |z2|
|z1 + z2| ≥ |z1| – |z2|
The point represented by the complex number 2 – i is rotated about origin through an angle `pi/2` in the clockwise direction, the new position of point is ______.
1 + 2i
–1 – 2i
2 + i
–1 + 2i
Let x, y ∈ R, then x + iy is a non-real complex number if ______.
x = 0
y = 0
x ≠ 0
y ≠ 0
If a + ib = c + id, then ______.
a2 + c2 = 0
b2 + c2 = 0
b2 + d2 = 0
a2 + b2 = c2 + d2
The complex number z which satisfies the condition `|(i + z)/(i - z)|` = 1 lies on ______.
Circle x2 + y2 = 1
The x-axis
The y-axis
The line x + y = 1.
If z is a complex number, then ______.
|z2| > |z|
|z2| = |z|2
|z2| < |z|2
|z2| ≥ |z|2
|z1 + z2| = |z1| + |z2| is possible if ______.
`z_2 = barz_1`
`z_2 = 1/z_1`
arg (z1) = arg (z2)
|z1| = |z2|
The real value of θ for which the expression `(1 + i cos theta)/(1 - 2i cos theta)` is a real number is ______.
`npi + pi/4`
`npi + (-1)n pi/4`
`2npi +- pi/2`
None of these
The value of arg (x) when x < 0 is ______.
0
`pi/2`
π
None of these
If f(z) = `(7 - z)/(1 - z^2)`, where z = 1 + 2i, then |f(z)| is ______.
`|z|/2`
|z|
2|z|
None of these
Chapter 5: Complex Numbers and Quadratic Equations
NCERT solutions for Mathematics Exemplar Class 11 chapter 5 - Complex Numbers and Quadratic Equations
NCERT solutions for Mathematics Exemplar Class 11 chapter 5 (Complex Numbers and Quadratic Equations) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Mathematics Exemplar Class 11 solutions in a manner that help students grasp basic concepts better and faster.
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Concepts covered in Mathematics Exemplar Class 11 chapter 5 Complex Numbers and Quadratic Equations are Argand Plane and Polar Representation, Quadratic Equations, Algebra of Complex Numbers - Equality, Algebraic Properties of Complex Numbers, Need for Complex Numbers, Square Root of a Complex Number, Algebra of Complex Numbers, The Modulus and the Conjugate of a Complex Number, Concept of Complex Numbers.
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