Complex number

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  • 1. GRAViitYCOMPLEX NUMBERMATHEMATICS-PI SECTION IStraight Objective Type This section contains 8 multiple choice questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONLY ONE is correct.21.If z and are two non-zero complex numbers such that |z| = 1 and Arg z Arg = z (A) 1 (C) i22.23.24. , then 2(B) 1 (D) iLet z and be complex numbers such that z i 0 and arg z = , then arg z = (A) (B) 4 2 3 5 (C) (D) 4 4 i z 1 e If the imaginary part of the expression i be zero, then locus of z is z 1 e (A) straight line (B) parabola (C) unit circle (D) ellipse If is a complex number such that || = r 1 then z between the foci is (A) 2 (C) 31 describes a conic. The distance (B) 2( 2 1) (D) 4z lie on 1 z2 (A) a line not passing through the origin (B) | z | 2 (C) the x-axis (D) the y-axis25.If |z| = 1 and z 1, then all the values of26.The number of solutions of the system of equations given by |z| = 3 and | z 1 i | 2 is equal to (A) 4 (B) 2 (C) 1 (D) no solution27.Let z = cos + isin. Then the value of151 Im(z2m1 ) m1 sin 2 1 (C) 2sin 2(A)28.1 3sin 2 1 (D) 4sin 2(B)In geometrical progression first term and common ratio are both value of the nth term of the progression is (A) 2n (C) 1BYat = 2 isRAJESH SIR(B) 4n (D) 3n1 ( 3 i). Then the absolute 2

2. GRAViitYCOMPLEX NUMBERSECTION IIMultiple Correct Answer Type This section contains 4 multiple correct answer(s) type questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONE OR MORE is/are correct.29.If z 20i 21 21 20i , then the principal value of arg z can be (A) 4(C) 3 4 3 (D) 4 (B) 430.If z1 = a + ib and z2 = c + id are complex numbers such that |z1| = |z2| = 1 and Re(z1z2) = 0 then the pair of complex numbers 1 = a + ic and 2 = b + id satisfies. (A) |1| = 1 (B) |2| = 1 (C) Re (1 2) = 0 (D) |1| = 231.If z1 = 5 + 12i and |z2| = 4 then (A) maximum (|z1 + iz2|) = 17 (C) minimum32.z1 4 z2 z2(B) minimum (|z1 + (1 + i)z2|) = 13 9 213 4(D) maximumz1 4 z2 z213 3If z is a complex number satisfying |z i Re(z)| = |z Im (z)| then z lies on (A) y = x (B) y = x (C) y = x + 1 (D) y = x + 1 SECTION IIILinked Comprehension Type This section contains 2 paragraphs. Based upon each paragraph, 3 multiple choice questions have to be answered. Each question has 4 choices (A), (B), (C) and (D) out of which ONLY ONE is correct.Paragraph for Question Nos. 33 to 35 Let A, B, C be three sets of complex numbers as defined below A = {z : Im z 1} B = {z : |z 2 i| = 3} C = {z : Re((1 i)z) = 2 } 33.The number of elements in the set ABC is (A) 0 (C) 2(B) 1 (D) 34.Let z be any point in ABC. Then, |z + 1 i|2 + |z 5 i|2 lies between (A) 25 and 29 (B) 30 and 34 (C) 35 and 39 (D) 40 and 4435.Let z be any point in ABC and let w be any point satisfying | 2 i| < 3. Then, |z| |w| + 3 lies between (A) 6 and 3 (B) 4 and 6 (C) 6 and 6 (D) 3 and 9BYRAJESH SIR 3. GRAViitYCOMPLEX NUMBER Paragraph for Question Nos. 36 to 38Suppose z and w be two complex numbers such that |z| 1, |w| 1 and |z + iw| = |z i w | = 2. Use the result | z |2 zz and |z + w| |z| + |w|, answer the following 36.Which of the following is true about |z| and ||1 2 3 (C) | z | | w | 4 (A) | z || w |37.38.(B) | z |1 3 , | w | 2 4(D) |z| = |w| = 1Which of the following is true for z and (A) Re(z) = Re(w) (C) Re(z) = Im(w)(B) Im(z) = Im(w) (D) Im(z) = Re(w)Number of complex numbers satisfying the above conditions is (A) 1 (B) 2 (C) 4 (D) indeterminate SECTION IV39.40.Matrix Match Type Match the statements/expressions in Column I with the open intervals in Column II Column I Column II 10 (A) (P) 2 sin 0 (r )(r ) 900 r 1 (B) If roots of t2 + t + 1 = 0 be , then 4 + 4 + (Q) 4 1 1 = 4 (C) 1 cos isin If cos n isin n, then n (R) i sin i(1 cos ) = (D) (S) If z r cos r isin r , r = 1,2,3,., then value 1 3 3 of z1z2z3 = Number of solutions of Column I (A) (B) (C) (D)BY2z |z| 0 22z z 0 z 2 8z 0 | z 2 | 1 and | z 1| 2RAJESH SIRColumn II (P)1(Q)3(R) (S)4 Infinite 4. GRAViitYCOMPLEX NUMBERMATHEMATICS-PII SECTION IStraight Objective Type This section contains 4 multiple choice questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONLY ONE is correct.20.The roots of 1 + z + z3 + z4 = 0 are represented by the vertices of (A) a square (B) an equilateral triangle (C) a rhombus (D) a rectangle21.If |z 1| + |z + 3| 8, then the range of values of |z 4| is, (A) (0, 8) (B) [1, 9] (C) [0, 8] (D) [5, 9]22.If z1, z2 and z3 be the vertices of ABC, taken in anti-clock wise direction and z0 be the z 0 z1 sin 2A z 0 z 3 sin 2C is equal to z 0 z 2 sin 2B z 0 z 2 sin 2B circumcentre, then (A) 0 (C) 1 23.(B) 1 (D) 2If a, b, c, a1,b1,c1 are non zero complex numbers satisfyinga b c 1 i and a1 b1 c1a1 b1 c1 a2 b2 c 2 0 , then 2 2 2 is equal to a b c a1 b1 c1 (A) 2i (C) 2(B) 2 + 2i (D) 2 2i SECTION IIMultiple Correct Answer Type This section contains 5 multiple correct answer(s) type questions. Each question has 4 choices (A), (B), (C) and (D), out of which ONE OR MORE is/are correct.24.A, B, C are the points representing the complex numbers z1, z2, z3 respectively on the complex plane and the circumcentre of the triangle ABC lies at the origin. If the altitude AD of the triangle ABC meets the circumcircle again at P, then P represents the complex number zz zz z z (A) z1z 2 z 3 (B) 1 2 (C) 1 3 (D) 2 3 z3 z2 z125.If points A and B are represented by the non-zero complex numbers z1 and z2 on the Argand plane such that |z1 + z2| = |z1 z2| and 0 is the origin, then z z (A) orthocentre of OAB lies at 0 (B) circumcentre of AOB is 1 2 2 z (C) arg 1 (D) OAB is isosceles 2 z2 26.If f(x) and g(x) are two polynomials such that the polynomial h(x) = xf(x3) + x2g(x6) is divisible by x2 + x + 1, then (A) f(1) = g(1) (B) f(1) = g(1) (C) h(1) = 0 (D) none of theseBYRAJESH SIR 5. GRAViitY27.28.COMPLEX NUMBERIf ( 1) is the fifth root of unity then (A) |1 2 3 4 | 0 (C) |1 2 | 2cos 5(B) |1 2 3 | 1 (D) |1 | 2cos 10If the lines az az b 0 and cz cz d 0 are mutually perpendicular, where a and c are non-zero complex numbers and b and d are real numbers, then (A) aa cc 0 (B) ac is purely imaginary a c a (C) arg (D) 2 a c cSECTION IIIMatrix Match Type 29.Match the statements/expressions in Column I with the open intervals in Column II Column I (A) (P) z 3 z2 Let z1, z2 be complex numbers such that 1 1 and |z2| 1, thenColumn II3 z1 z26|z1| is equal to (B) (C) (D)30.Number of non-zero complex number satisfying z iz 2 Let a, b (0, 1) and z1 = a + i, z2 = 1 + bi and z3 = 0 be the vertices of an equilateral triangle then value of a b 2 3 is equal to Consider a circle having OP as diameter where O being origin and P be z1. Take two points Q(z2) and R(z3) on the circle and also on the same4(R)3(S)3 2 side of OP. If POQ =/2k, QOR = /k and 8 z2 (5 3 3) z1 z3 then k is equal to Let the complex numbers z1, z2 and z3 represent the vertices A, B and C of triangle ABC respectively, which is inscribed in the circle of radius unity and centre at origin. The internal bisector of the angle A meets the circumcircle again at the point D, which is represent by the complex number z4, and altitude from A to BC meets the circumcircle at E, given by z5. Now match the entries from the following columns Column I Column II (A) (P) z z arg 2 2 3 is equal to z4 (B) (C) (D) z4 arg is equal to z 2 z3 zz arg 1 3 is equal to z 2 z5 (Q) z2 arg 4 z1z 5 (S)(R)RAJESH SIR 2 40 (T)BY(Q) /25 6. GRAViitYCOMPLEX NUMBERSECTION IVInteger Answer Type This section contains 8 questions. The answer to each of the question is a single digit integer, ranging from 0 to 9. The appropriate bubbles below the respective question numbers in the ORS have to be darkened. For example, if the correct answers to question numbers X, Y, Z and W (say) are 6, 0, 9 and 2, respectively, then the correct darkening of bubbles will look like the following:a b c 0 where a, b, c are three distinct complex numbers, then the value of bc ca a b a2 b2 c2 is equal to (b c) 2 (c a) 2 (a b) 231.If32.If |z1| = 1, |z2| = 2, |z3| = 3 and |9 z1z2 + 4z1z3 + z2z3| = 12 then |z1 + z2 + z3| is equal to33. 3z 6 3i If the complex numbers z for which arg and |z 3 + i| = 3, are 2z 8 6i 4 4 2 4 2 k i 1 and k i 1 then k must be equal to 5 5 5 5 2034.If e 2 i/7 and f x A 0 A k x k then the value of f(x) + f(x) + f(2x) + . + f(6x) k 1is k(A0 + A7x7 + A14x14), then k must be equal to 35.If magnitude of a complex number 4 3i is tripled and rotated by an angle anticlockwise about origin then resulting complex number would 12 + i then must be equal to36.The maximum value of |z| when z satisfies the condition z 37.Let z1, z2 be the roots of the equation z2 + az + b = 0 where a and b may be complex. Let A and B represent z1 and z2 in the Argands plane. If AOB 0 and OA = OB. Then 2 = b cos2 . where value is 238.z1, z2 are roots of the equation z2 + az + b = 0. If AOB (0 is origin), A and B represent z1 and a2 z2 is equilateral, then is equal to .. bBYRAJESH SIR2 2 is 1 z 7. GRAViitYCOMPLEX NUMBERPAPER I KEYMATHS 21. (D) 22. (C) 23. (C) 24. (D) 25. (D) 26. (D) 27. (D) 28. (C) 29. (ABCD) 30. (ABC) 31. (AD) 32. (AB) 33. (B) 34. (C) 35. (D) 36. (D) 37. (D) 38. (B) 39. (A - S), (B - P), (C - Q), (D - R) 40. (A- Q), (B - S), (C - R), (D P) PAPER II KEYMATHS 20. (B) 21. (B) 22. (C) 23. (A) 24. (BCD) 25. (ABC) 26. (ABC) 27. (ABC) 28. (BC) 29. (A-R), (B-R), (C-Q), (D-P) 30. (A S), (B QT), (C S), (D P) 31. 2 32. 2 33. 4 34. 7 35. 9 36. 3 37. 4 38. 3BYRAJESH SIR