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If z1 is a root of the equation a0z^n+a1...

If `z_1` is a root of the equation `a_0z^n+a_1z^(n-1)++a_(n-1)z+a_n=3,w h e r e|a_i|<2fori=0,1, ,n ,t h e n` `|z|=3/2` b. `|z|<1/4` c.`|z|>1/4` d. `|z|<1/3`

A

`|z_(1)|gt(1)/(2)`

B

`|z_(1)|lt(1)/(2)`

C

`|z_(1)|gt(1)/(4)`

D

`|z| lt(1)/(2)`

Text Solution

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The correct Answer is:
To solve the problem, we need to analyze the given polynomial equation and apply properties of complex numbers and inequalities. Let's break down the solution step by step. ### Step-by-Step Solution: 1. **Given Equation**: We have the polynomial equation \[ a_0 z^n + a_1 z^{n-1} + \ldots + a_{n-1} z + a_n = 3 \] where \(|a_i| < 2\) for \(i = 0, 1, \ldots, n\). 2. **Taking Modulus**: Taking the modulus of both sides, we get: \[ |a_0 z^n + a_1 z^{n-1} + \ldots + a_n| = |3| = 3 \] 3. **Applying Triangle Inequality**: By the triangle inequality, we have: \[ |a_0 z^n| + |a_1 z^{n-1}| + \ldots + |a_n| \geq |3| \] Therefore, \[ |a_0 z^n| + |a_1 z^{n-1}| + \ldots + |a_n| \geq 3 \] 4. **Substituting the Bounds on Coefficients**: Since \(|a_i| < 2\), we can write: \[ |a_0| < 2, |a_1| < 2, \ldots, |a_n| < 2 \] Thus, \[ |a_0 z^n| + |a_1 z^{n-1}| + \ldots + |a_n| < 2|z|^n + 2|z|^{n-1} + \ldots + 2 \] 5. **Factoring Out the Common Term**: We can factor out \(2\): \[ |a_0 z^n| + |a_1 z^{n-1}| + \ldots + |a_n| < 2(|z|^n + |z|^{n-1} + \ldots + 1) \] 6. **Geometric Series**: The sum \( |z|^n + |z|^{n-1} + \ldots + 1 \) is a geometric series. Its sum can be expressed as: \[ \frac{|z|^{n+1} - 1}{|z| - 1} \quad \text{(for } |z| \neq 1\text{)} \] 7. **Setting Up the Inequality**: We can now set up the inequality: \[ 3 \leq 2 \cdot \frac{|z|^{n+1} - 1}{|z| - 1} \] Simplifying this gives: \[ 3(|z| - 1) \leq 2(|z|^{n+1} - 1) \] 8. **Rearranging the Terms**: Rearranging gives: \[ 2|z|^{n+1} - 3|z| + 2 - 3 \geq 0 \] which simplifies to: \[ 2|z|^{n+1} - 3|z| - 1 \geq 0 \] 9. **Finding the Bound**: To find the bounds for \(|z|\), we need to analyze the roots of the polynomial \(2x^{n+1} - 3x - 1 = 0\). We can use the Rational Root Theorem or numerical methods to find the approximate roots. 10. **Conclusion**: After analyzing the behavior of the polynomial, we conclude that: \[ |z| > \frac{1}{3} \] ### Final Answer: Thus, the correct answer is: **c. \(|z| > \frac{1}{4}\)**

To solve the problem, we need to analyze the given polynomial equation and apply properties of complex numbers and inequalities. Let's break down the solution step by step. ### Step-by-Step Solution: 1. **Given Equation**: We have the polynomial equation \[ a_0 z^n + a_1 z^{n-1} + \ldots + a_{n-1} z + a_n = 3 \] ...
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