Question
upstudy study bank question image url

2. If \( \alpha, \beta \) are the roots of \( 3 x^{2}+2 x+1=0 \), then find the equation whose roots are \( \frac{1-\alpha}{1+\alpha} \) and \( \frac{1-\beta}{1+\beta} \)

Ask by Cole Curry. in India
Jan 24,2025

Real Tutor Solution

Tutor-Verified Answer

Answer

The equation with roots \( \frac{1-\alpha}{1+\alpha} \) and \( \frac{1-\beta}{1+\beta} \) is \( y^{2} - 2\,y + 3 = 0 \).

Solution

To find the equation whose roots are \( \frac{1-\alpha}{1+\alpha} \) and \( \frac{1-\beta}{1+\beta} \), where \( \alpha \) and \( \beta \) are the roots of the quadratic equation \( 3x^2 + 2x + 1 = 0 \), follow these steps: ### 1. Express \( \alpha \) in terms of \( y \) Let \( y = \frac{1 - \alpha}{1 + \alpha} \). We can solve for \( \alpha \) as follows: \[ y(1 + \alpha) = 1 - \alpha \\ y + y\alpha = 1 - \alpha \\ \alpha(y + 1) = 1 - y \\ \alpha = \frac{1 - y}{1 + y} \] ### 2. Substitute \( \alpha \) into the original equation Substitute \( \alpha = \frac{1 - y}{1 + y} \) into \( 3\alpha^2 + 2\alpha + 1 = 0 \): \[ 3\left(\frac{1 - y}{1 + y}\right)^2 + 2\left(\frac{1 - y}{1 + y}\right) + 1 = 0 \] Multiply through by \( (1 + y)^2 \) to eliminate the denominator: \[ 3(1 - 2y + y^2) + 2(1 - y^2) + (1 + 2y + y^2) = 0 \] Expand and simplify: \[ 3 - 6y + 3y^2 + 2 - 2y^2 + 1 + 2y + y^2 = 0 \\ (3y^2 - 2y^2 + y^2) + (-6y + 2y) + (3 + 2 + 1) = 0 \\ 2y^2 - 4y + 6 = 0 \] Divide the entire equation by 2: \[ y^2 - 2y + 3 = 0 \] ### Verification Using Sum and Product of Roots Alternatively, you can verify by finding the sum and product of the new roots \( y_1 \) and \( y_2 \): - **Sum of roots**: \[ y_1 + y_2 = 2 \] - **Product of roots**: \[ y_1y_2 = 3 \] Thus, the quadratic equation is: \[ y^2 - 2y + 3 = 0 \] ### Final Answer \[ y^{2} - 2\,y + 3 = 0 \]

Reviewed and approved by the UpStudy tutoring team

error msg
Explain
Simplify this solution

Beyond the Answer

To find the equation with roots \(\frac{1-\alpha}{1+\alpha}\) and \(\frac{1-\beta}{1+\beta}\), we can use the given quadratic equation \(3x^2 + 2x + 1 = 0\). ### Step 1: Find \(\alpha + \beta\) and \(\alpha \beta\) For the quadratic \(ax^2 + bx + c = 0\), the roots \(\alpha\) and \(\beta\) satisfy: \[ \alpha + \beta = -\frac{b}{a} = -\frac{2}{3}, \quad \alpha \beta = \frac{c}{a} = \frac{1}{3}. \] ### Step 2: Find the new roots The transformation to the new roots can be represented as: \[ y = \frac{1-x}{1+x}. \] Solving for \(x\) gives: \[ x = \frac{1-y}{1+y}. \] Using Vieta's formulas, we express \(s = \frac{1-\alpha}{1+\alpha} + \frac{1-\beta}{1+\beta}\) and \(p = \frac{(1-\alpha)(1-\beta)}{(1+\alpha)(1+\beta)}\). #### Finding \(s\): \[ s = \frac{(1-\alpha)(1+\beta) + (1-\beta)(1+\alpha)}{(1+\alpha)(1+\beta)} = \frac{1 - \alpha + \beta - \alpha\beta + 1 - \beta + \alpha - \alpha\beta}{(1+\alpha)(1+\beta)} = \frac{2 - 2\alpha\beta}{(1+\alpha)(1+\beta)}. \] Substituting \(\alpha + \beta = -\frac{2}{3}\) and \(\alpha \beta = \frac{1}{3}\): \[ s = \frac{2 - 2\cdot\frac{1}{3}}{(1 - \frac{2}{3})(1 - \frac{2}{3})} = \frac{2 - \frac{2}{3}}{\left(\frac{1}{3}\right)\left(\frac{1}{3}\right)} = \frac{\frac{4}{3}}{\frac{1}{9}} = 12. \] #### Finding \(p\): \[ p = \frac{(1-\alpha)(1-\beta)}{(1+\alpha)(1+\beta)} = \frac{1 - (\alpha+\beta) + \alpha\beta}{1 + (\alpha+\beta) + \alpha\beta}. \] Substituting the values gives: \[ p = \frac{1 + \frac{2}{3} + \frac{1}{3}}{1 - \frac{2}{3} + \frac{1}{3}} = \frac{1 + 1}{1 - \frac{1}{3}} = \frac{2}{\frac{2}{3}} = 3. \] ### Step 3: Form the quadratic equation The new quadratic equation whose roots are \(y_1\) and \(y_2\) is given by: \[ x^2 - sx + p = 0 \implies x^2 - 12x + 3 = 0. \] Thus, the equation with roots \(\frac{1-\alpha}{1+\alpha}\) and \(\frac{1-\beta}{1+\beta}\) is \[ \boxed{x^2 - 12x + 3 = 0}. \]

Try Premium now!
Try Premium and ask Thoth AI unlimited math questions now!
Maybe later Go Premium
Study can be a real struggle
Why not UpStudy it?
Select your plan below
Premium

You can enjoy

Start now
  • Step-by-step explanations
  • 24/7 expert live tutors
  • Unlimited number of questions
  • No interruptions
  • Full access to Answer and Solution
  • Full Access to PDF Chat, UpStudy Chat, Browsing Chat
Basic

Totally free but limited

  • Limited Solution
Welcome to UpStudy!
Please sign in to continue the Thoth AI Chat journey
Continue with Email
Or continue with
By clicking “Sign in”, you agree to our Terms of Use & Privacy Policy