Question:

If $z(2-i)=(3+i)$, then $z^{20}$ is equal to

Updated On: Sep 24, 2024
  • $2^{10}$
  • $-2^{10}$
  • $2^{20}$
  • $-2^{20}$
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The Correct Option is B

Solution and Explanation

We have, $z\left(2-i\right)=\left(3+i\right)$ $\Rightarrow\, z=\left(\frac{3+i}{2-i}\right)\times\left(\frac{2+i}{2+i}\right)$ $=\frac{5+5i}{5}$ $\Rightarrow\, z=1+i$ $\Rightarrow\, z^{2}=2i$ $\Rightarrow\, z^{20}$ $=-2^{10}$
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Concepts Used:

Complex Numbers and Quadratic Equations

Complex Number: Any number that is formed as a+ib is called a complex number. For example: 9+3i,7+8i are complex numbers. Here i = -1. With this we can say that i² = 1. So, for every equation which does not have a real solution we can use i = -1.

Quadratic equation: A polynomial that has two roots or is of the degree 2 is called a quadratic equation. The general form of a quadratic equation is y=ax²+bx+c. Here a≠0, b and c are the real numbers.