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JEE • MATHEMATICS • COMPLEX NUMBERS

Complex numbers practice · Mixed difficulty

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These sets use single-correct-answer MCQs. They do not cover every JEE Main or JEE Advanced question format and are not full-length mock papers.

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211 Medium
211 of 979
Application +4 | -1
If mm and xx are two real numbers, then e2micot⁡−1x(xi+1xi−1)me^{2 m i \cot ^{-1} x}\left(\frac{x i+1}{x i-1}\right)^m (where i=−1i=\sqrt{-1} ) is equal to
View answer and explanation
Correct option: A
1
Option A (1) is correct because the expression simplifies to 1 using trigonometric identities and Euler's formula.
212 Easy
212 of 979
Application +4 | -1
If ω=e−2πi/3,a,b,c,x,y,z\omega=e^{-2 \pi i / 3}, a, b, c, x, y, z are non-zero complex numbers such that a+b+c=x,a+bω+cω2=ya+b+c=x, a+b \omega+c \omega^2=y and a+a+ bω2+cω=zb \omega^2+c \omega=z, then ∣x∣2+∣y∣2+∣z∣2∣a∣2+∣b∣2+∣∣2=\frac{|x|^2+|y|^2+|z|^2}{|a|^2+|b|^2+||^2}=
View answer and explanation
Correct option: D
9
Option D (9) is correct because, given the conditions and substituting a=b=c, x=3a, y=0, z=0, the expression simplifies to 9.
213 Easy
213 of 979
Application +4 | -1
If 7log⁡7(x2−4  x+5)=x−1,x{7^{{{\log }_7}\left( {{x^2} - 4\;x + 5} \right)}} = x - 1,x may have values
View answer and explanation
Correct option: A
2,  32,\;3
Option A (2, 3) is correct because these values satisfy the given equation when substituted and checked for validity within the logarithmic function.
214 Medium
214 of 979
Application +4 | -1
Let z=cos⁡θ+isin⁡θz=\cos \theta+i \sin \theta. Then value of ∑m=115Im⁡(z2m−1)\sum\limits_{{m=1}}^{15} \operatorname{Im}\left(z^{2 m-1}\right) at θ=3∘\theta=3^{\circ} is
View answer and explanation
Correct option: C
12sin⁡3∘\frac{1}{2 \sin 3^{\circ}}
Option C (12sin⁡3∘\frac{1}{2 \sin 3^{\circ}}) is correct because the summation simplifies to an imaginary part involving a geometric series, which can be evaluated using the formula for the sum of a geometric series.
215 Easy
215 of 979
Application +4 | -1
The value of (1+i)5(1−i)5(1+i)^5(1-i)^5 is 2n,2^n, 'nn' is equal to
View answer and explanation
Correct option: A
5
Option A (5) is correct because (1+i)5(1−i)5(1+i)^5(1-i)^5 simplifies to 252^5, thus n=5.
216 Easy
216 of 979
Application +4 | -1
The value of i592+i590+i588+i586+i584i582+i580+i578+i576+i574−1\frac{i^{592}+i^{590}+i^{588}+i^{586}+i^{584}}{i^{582}+i^{580}+i^{578}+i^{576}+i^{574}}-1 is
View answer and explanation
Correct option: B
-2
Option C (-2) is correct because after simplification, the expression equals -2.
217 Easy
217 of 979
Application +4 | -1
If z1=2+3iz_1=2+3 i and z2=3−2iz_2=3-2 i, then z1−z2z_1-z_2 equals to −1+bi.-1+ bi. The value of 'bb' is
View answer and explanation
Correct option: A
5
Option A (5) is correct because subtracting z2 from z1 results in -1 + 5i, so the value of 'b' is 5.
218 Medium
218 of 979
Application +4 | -1
The square roots of −2+23i-2+2 \sqrt{3} i are
View answer and explanation
Correct option: A
±(1+3i)\pm(1+\sqrt{3} i)
Option A is correct because the square roots of −2+23i-2+2\sqrt{3}i are ±(1+3i)\pm(1+\sqrt{3}i).
219 Easy
219 of 979
Understanding +4 | -1
If z≠0z \neq 0, then ∫x=0100[arg⁡∣z∣]dx\int\limits_{{x=0}}^{100}[\arg |z|] d x is (where [∗][*] denotes the greatest integer function)
View answer and explanation
Correct option: A
0
Option A is correct because the argument of the absolute value of any non-zero complex number is always 0, and the greatest integer function of 0 is 0.
220 Easy
220 of 979
Application +4 | -1
The mirror image of the curve arg⁡(z+iz−1)=π4\arg \left(\frac{z+i}{z-1}\right)=\frac{\pi}{4}, i=−1i=\sqrt{-1} in the line x−y=0x-y=0, is
View answer and explanation
Correct option: C
arg⁡(z−iz+1)=π4\arg \left(\frac{z-i}{z+1}\right)=\frac{\pi}{4}
Option C (arg⁡(z−iz+1)=π4\arg \left(\frac{{z - i}}{{z + 1}}\right) = \frac{\pi }{4}) is correct because the mirror image of a complex number z in the line x-y=0 is obtained by swapping the real and imaginary parts, which is equivalent to taking izˉi\bar{z}.
221 Easy
221 of 979
Application +4 | -1
Let zz be a complex number such that ∣z−iz+2i∣=1\left| {\frac{{z - i}}{{z + 2i}}} \right| = 1 and ∣z∣=52.\left| z \right| = \frac{5}{2}. Then the value of ∣z+3i∣\left| {z + 3i} \right| is
View answer and explanation
Correct option: B
72\frac{7}{2}
Option B (7/2) is correct because, after finding the locus of z and using the given modulus condition, we can determine |z + 3i| = 7/2.
222 Easy
222 of 979
Application +4 | -1
If ∣z∣=z+3−2i|z|=z+3-2 i, then zz equals
View answer and explanation
Correct option: C
−5/6+2i-5 / 6+2 i
Option C (-5/6 + 2i) is correct because solving the equation |z| = z + 3 - 2i for z yields z = -5/6 + 2i.
223 Medium
223 of 979
Application +4 | -1
If Im⁡(z+2iz+2)=0\operatorname{Im}\left(\frac{z+2 i}{z+2}\right)=0, then zz lies on the curve
View answer and explanation
Correct option: C
x+y+2=0x+y+2=0
Option C (x+y+2=0x+y+2=0) is correct because the imaginary part of the given expression being zero implies that z lies on the line x+y+2=0.
224 Easy
224 of 979
Application +4 | -1
If z1=2(cos⁡π4+isin⁡π4){z_1} = \sqrt 2 \left( {\cos \frac{\pi }{4} + i\sin \frac{\pi }{4}} \right) And z2=3(cos⁡π3+isin⁡π3){z_2} = \sqrt 3 \left( {\cos \frac{\pi }{3} + i\sin \frac{\pi }{3}} \right), then ∣z1z2∣\left| {{z_1}{z_2}} \right| is
View answer and explanation
Correct option: C
6\sqrt 6
The correct answer is C (6\sqrt 6) because the modulus of the product of two complex numbers is the product of their moduli.
225 Medium
225 of 979
Application +4 | -1
If 349(x+iy)=(32+i32)1003^{49}(x+i y)=\left(\frac{3}{2}+i \frac{\sqrt{3}}{2}\right)^{100} and x=kyx=k y, then kk is
View answer and explanation
Correct option: D
−13-\frac{1}{\sqrt{3}}
The value of k is −13-\frac{1}{\sqrt{3}} because it is found by simplifying the given complex number equation and comparing the real and imaginary parts.
226 Easy
226 of 979
Analyzing +4 | -1
Let z(≠2)z\left( { \ne 2} \right) be a complex number such that log⁡1/2∣z−2∣>log⁡1/2∣z∣,{\log _{1/2}}\left| {z - 2} \right| > {\log _{1/2}}\left| z \right|, then
View answer and explanation
Correct option: A
Re  (z)>1\mathrm{Re\;}\left( z \right) > 1
Option A (Re  (z)>1\mathrm{Re\;}\left( z \right) > 1) is correct because the inequality implies that the distance from z to 2 is less than the distance from z to 0, meaning z lies to the right of the perpendicular bisector of the segment joining 0 and 2.
227 Easy
227 of 979
Application +4 | -1
The conjugate of complex number 2−3i4−i\frac{{2 - 3i}}{{4 - i}} is
View answer and explanation
Correct option: B
11+10i17\frac{{11 + 10i}}{{17}}
Option B (11+10i17\frac{{11 + 10i}}{{17}}) is correct because it is the result of finding the conjugate of the given complex number and simplifying the expression.
228 Medium
228 of 979
Application +4 | -1
If xr=cos⁡(π/3r)x_r=\cos \left(\pi / 3^r\right) - i sin⁡(π/3r)\sin \left(\pi / 3^r\right), (where i=−1i=\sqrt{-1} ). then value of x1⋅x2⋅…∞x_1 \cdot x_2 \cdot \ldots \infty, is
View answer and explanation
Correct option: C
−i-{i}
Option C (-i) is correct because the product simplifies to -i using the properties of complex numbers and infinite geometric series.
229 Easy
229 of 979
Application +4 | -1
If ω\omega is a complex cube root of unity, then 225+(3ω+8ω2)2+(3ω2+8ω)2225 + {\left( {3\omega + 8{\omega ^2}} \right)^2} + {\left( {3{\omega ^2} + 8\omega } \right)^2} is equal to
View answer and explanation
Correct option: D
248
Option D (248) is correct because it is the result of simplifying the expression using the properties of complex cube roots of unity.
230 Easy
230 of 979
Application +4 | -1
Let zz be a complex number such that ∣z∣+z=3+i\left| z \right| + z = 3 + i (where i=−1)i = \sqrt { - 1} ). Then ∣z∣\left| z \right| is equal to
View answer and explanation
Correct option: B
53\frac{5}{3}
Option B (5/3) is correct because by substituting z=x+iz = x + i into the given equation and solving for x, we can find the magnitude of z.
231 Easy
231 of 979
Understanding +4 | -1
Let z1{z_1} and z2{z_2} be two complex numbers with α\alpha and β\beta as their principle arguments such that α+β>π,\mathrm{\alpha } + \mathrm{\beta } > \mathrm{\pi }, then principal arg⁡(z1z2)  \arg \left( {{z_1}{z_2}} \right)\; is given by
View answer and explanation
Correct option: B
α+β−π\mathrm{\alpha } + \mathrm{\beta } - \mathrm{\pi }
Option B (α+β−π\alpha + \beta - \pi) is correct because the principal argument must lie between −π-\pi and π\pi, and since α+β>π\alpha + \beta > \pi, we subtract 2π2\pi to bring it into the range.
232 Easy
232 of 979
Understanding +4 | -1
The complex numbers z1,z2,z3,z4{z_1},{z_2},{z_3},{z_4} taken in that order in the Argand plane represent the vertices of a parallelogram iff
View answer and explanation
Correct option: B
z1+z3=z2+z4{z_1} + {z_3} = {z_2} + {z_4}
Option B (z1+z3=z2+z4{z_1} + {z_3} = {z_2} + {z_4}) is correct because in a parallelogram, the sum of opposite vertices are equal.
233 Easy
233 of 979
Application +4 | -1
If 1,  ω,  ω21,\;\omega ,\;{\omega ^2} are the cube roots of unity, then (3+ω2+ω4)6{\left( {3 + {\omega ^2} + {\omega ^4}} \right)^6} is equal to
View answer and explanation
Correct option: A
64
Option A (64) is correct because simplifying the expression using the properties of cube roots of unity results in 26 = 64.
234 Hard
234 of 979
Analyzing +4 | -1
The value of the expression
2(1+1ω)(1+1ω2)+3(2+1ω)(2+1ω2)+…+(n+1)(n+1ω)(n+1ω2)2\left( {1 + \frac{1}{\omega }} \right)\left( {1 + \frac{1}{{{\omega ^2}}}} \right) + 3\left( {2 + \frac{1}{\omega }} \right)\left( {2 + \frac{1}{{{\omega ^2}}}} \right) + \ldots + \left( {n + 1} \right)\left( {n + \frac{1}{\omega }} \right)\left( {n + \frac{1}{{{\omega ^2}}}} \right) is
View answer and explanation
Correct option: C
[n(n+1)2]2+n{\left[ {\frac{{n\left( {n + 1} \right)}}{2}} \right]^2} + n
Option C ([n(n+1)2]2+n{\left[ {\frac{{n\left( {n + 1} \right)}}{2}} \right]^2} + n) is correct because by simplifying the expression using properties of complex cube roots of unity, we can derive the given result.
235 Easy
235 of 979
Analyzing +4 | -1
Let a circle CC in complex plane pass through the points z1=3+4i,  z2=4+3i{z_1} = 3 + 4i,\,\,{z_2} = 4 + 3i and  z3=5i. \,{z_3} = 5i.\, If z(≠z1)z( \ne {z_1}) sis point on CC such that the line through zz and z1{z_1} is perpendicular to the line through z2{z_2} and z3{z_3} then arg⁡(z)\arg (z) is equal to:
View answer and explanation
Correct option: B
tan⁡−1(247)−π{\tan ^{ - 1}}\left( {\frac{{24}}{7}} \right) - \pi
The correct answer is B (tan⁡−1(247)−π{\tan ^{ - 1}}\left( {\frac{{24}}{7}} \right) - \pi) because it is the argument of the point z on the circle, calculated using the given conditions and complex number properties.
236 Easy
236 of 979
Application +4 | -1
If ω\omega and ω2{\omega ^2} are the two imaginary cube roots of unity, then the equation whose roots are aω317a{\omega ^{317}} and aω382a{\omega ^{382}}, is
View answer and explanation
Correct option: A
x2+ax+a2=0{x^2} + ax + {a^2} = 0
Option A (x2+ax+a2=0{x^2} + ax + {a^2} = 0) is correct because it is the quadratic equation formed using the given roots and properties of cube roots of unity.
237 Medium
237 of 979
Application +4 | -1
If z≠0z \neq 0 be a complex number such that ∣z−1z∣=2\left|z-\frac{1}{z}\right|=2, then the maximum value of ∣z∣|z| is
View answer and explanation
Correct option: D
2+1\sqrt{2}+1
Option D (2+1\sqrt{{2}}+1) is correct because by using the triangle inequality and solving the resulting quadratic, we find the maximum value of |z|.
238 Medium
238 of 979
Application +4 | -1
If z1=3+i3z_1=\sqrt{3}+i \sqrt{3} and z2=3+iz_2=\sqrt{3}+i, then the complex number (z1z2)50\left(\frac{z_1}{z_2}\right)^{50} lies in the quadrant number
View answer and explanation
Correct option: A
I
Option A (I) is correct because after simplification, the complex number lies in the first quadrant.
239 Medium
239 of 979
Analyzing +4 | -1
The locus of the complex number zz in an argand plane satisfying the inequality log⁡1/2(∣z−1∣+43∣z−1∣−2)>1(\log _{1 / 2}\left(\frac{|z-1|+4}{3|z-1|-2}\right) > 1\left(\right. where, ∣z−1∣≠23)\left.|z-1| \neq \frac{2}{3}\right) is
View answer and explanation
Correct option: C
exterior of a circle
Option C (exterior of a circle) is correct because the inequality simplifies to ∣z−1∣>3|z-1| > 3, which represents the region outside a circle centered at 1 with radius 3.
240 Easy
240 of 979
Understanding +4 | -1
arg (zˉ)\left( {\bar z} \right) is equal to
View answer and explanation
Correct option: B
2π−arg⁡(z)2\mathrm{\pi } - \arg \left( z \right)
Option B (2π - arg(z)) is correct because the argument of the conjugate of a complex number is the negative of the argument of the original number, or 2π minus the argument.
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