Equation with nonlinearly transformed roots

Find a new polynomial whose roots are nonlinear transformations of the original roots (e.g., α², 1/α, αβ, α/βγ, (4α+1)/(α+1)), requiring more complex manipulation of symmetric functions or substitution.

39 questions · Challenging +1.1

4.05a Roots and coefficients: symmetric functions4.05b Transform equations: substitution for new roots
Sort by: Default | Easiest first | Hardest first
OCR Further Pure Core AS 2022 June Q3
6 marks Challenging +1.2
3 In this question you must show detailed reasoning. The roots of the equation \(5 x ^ { 3 } - 3 x ^ { 2 } - 2 x + 9 = 0\) are \(\alpha , \beta\) and \(\gamma\).
Find a cubic equation with integer coefficients whose roots are \(\alpha \beta , \beta \gamma\) and \(\gamma \alpha\).
OCR Further Pure Core 2 2022 June Q3
6 marks Challenging +1.2
3 In this question you must show detailed reasoning. The roots of the equation \(4 x ^ { 3 } + 6 x ^ { 2 } - 3 x + 9 = 0\) are \(\alpha , \beta\) and \(\gamma\). Find a cubic equation with integer coefficients whose roots are \(\alpha + \beta , \beta + \gamma\) and \(\gamma + \alpha\).
AQA FP2 2008 January Q4
14 marks Standard +0.3
4 The cubic equation $$z ^ { 3 } + \mathrm { i } z ^ { 2 } + 3 z - ( 1 + \mathrm { i } ) = 0$$ has roots \(\alpha , \beta\) and \(\gamma\).
  1. Write down the value of:
    1. \(\alpha + \beta + \gamma\);
    2. \(\alpha \beta + \beta \gamma + \gamma \alpha\);
    3. \(\alpha \beta \gamma\).
  2. Find the value of:
    1. \(\alpha ^ { 2 } + \beta ^ { 2 } + \gamma ^ { 2 }\);
    2. \(\alpha ^ { 2 } \beta ^ { 2 } + \beta ^ { 2 } \gamma ^ { 2 } + \gamma ^ { 2 } \alpha ^ { 2 }\);
    3. \(\alpha ^ { 2 } \beta ^ { 2 } \gamma ^ { 2 }\).
  3. Hence write down a cubic equation whose roots are \(\alpha ^ { 2 } , \beta ^ { 2 }\) and \(\gamma ^ { 2 }\).
OCR Further Pure Core AS 2019 June Q5
9 marks Standard +0.8
5 In this question you must show detailed reasoning. You are given that \(\alpha , \beta\) and \(\gamma\) are the roots of the equation \(5 x ^ { 3 } - 2 x ^ { 2 } + 3 x + 1 = 0\).
  1. Find the value of \(\alpha ^ { 2 } \beta ^ { 2 } + \beta ^ { 2 } \gamma ^ { 2 } + \gamma ^ { 2 } \alpha ^ { 2 }\).
  2. Find a cubic equation whose roots are \(\alpha ^ { 2 } , \beta ^ { 2 }\) and \(\gamma ^ { 2 }\) giving your answer in the form \(a x ^ { 3 } + b x ^ { 2 } + c x + d = 0\) where \(a , b , c\) and \(d\) are integers.
OCR FP1 AS 2021 June Q3
7 marks Challenging +1.8
3 In this question you must show detailed reasoning.
The cubic equation \(5 x ^ { 3 } + 3 x ^ { 2 } - 4 x + 7 = 0\) has roots \(\alpha , \beta\) and \(\gamma\).
Find a cubic equation with integer coefficients whose roots are \(\alpha + \beta , \beta + \gamma\) and \(\gamma + \alpha\).
OCR Further Pure Core 2 2021 June Q1
6 marks Challenging +1.2
1 In this question you must show detailed reasoning.
The roots of the equation \(3 x ^ { 3 } - 2 x ^ { 2 } - 5 x - 4 = 0\) are \(\alpha , \beta\) and \(\gamma\).
  1. Find a cubic equation with integer coefficients whose roots are \(\alpha ^ { 2 } , \beta ^ { 2 }\) and \(\gamma ^ { 2 }\).
  2. Find the exact value of \(\frac { \alpha ^ { 2 } \beta ^ { 2 } + \beta ^ { 2 } \gamma ^ { 2 } + \gamma ^ { 2 } \alpha ^ { 2 } } { \alpha \beta \gamma }\).
CAIE Further Paper 1 2024 November Q3
10 marks Challenging +1.8
The quartic equation \(x^4 + 2x^3 - 1 = 0\) has roots \(\alpha, \beta, \gamma, \delta\).
  1. Find a quartic equation whose roots are \(\alpha^4, \beta^4, \gamma^4, \delta^4\) and state the value of \(\alpha^4 + \beta^4 + \gamma^4 + \delta^4\). [5]
  2. Find the value of \(\alpha^5 + \beta^5 + \gamma^5 + \delta^5\). [3]
  3. Find the value of \(\alpha^8 + \beta^8 + \gamma^8 + \delta^8\). [2]
CAIE FP1 2019 November Q7
9 marks Challenging +1.3
The equation \(x^3 + 2x^2 + x + 7 = 0\) has roots \(\alpha\), \(\beta\), \(\gamma\).
  1. Use the relation \(x^2 = -7y\) to show that the equation $$49y^3 + 14y^2 - 27y + 7 = 0$$ has roots \(\frac{\alpha}{\beta \gamma}\), \(\frac{\beta}{\gamma \alpha}\), \(\frac{\gamma}{\alpha \beta}\). [4]
  2. Show that \(\frac{\alpha^2}{\beta^2 \gamma^2} + \frac{\beta^2}{\gamma^2 \alpha^2} + \frac{\gamma^2}{\alpha^2 \beta^2} = \frac{58}{49}\). [3]
  3. Find the exact value of \(\frac{\alpha^2}{\beta^3 \gamma^3} + \frac{\beta^2}{\gamma^3 \alpha^3} + \frac{\gamma^2}{\alpha^3 \beta^3}\). [2]
AQA FP1 2014 June Q2
11 marks Standard +0.3
The quadratic equation $$2x^2 + 8x + 1 = 0$$ has roots \(\alpha\) and \(\beta\).
  1. Write down the value of \(\alpha + \beta\) and the value of \(\alpha\beta\). [2 marks]
    1. Find the value of \(\alpha^2 + \beta^2\). [2 marks]
    2. Hence, or otherwise, show that \(\alpha^4 + \beta^4 = \frac{449}{2}\). [2 marks]
  2. Find a quadratic equation, with integer coefficients, which has roots $$2\alpha^4 + \frac{1}{\beta^2} \text{ and } 2\beta^4 + \frac{1}{\alpha^2}$$ [5 marks]
OCR FP1 2010 June Q7
7 marks Standard +0.8
The quadratic equation \(x^2 + 2kx + k = 0\), where \(k\) is a non-zero constant, has roots \(\alpha\) and \(\beta\). Find a quadratic equation with roots \(\frac{\alpha + \beta}{\alpha}\) and \(\frac{\alpha + \beta}{\beta}\). [7]
SPS SPS ASFM 2020 May Q4
9 marks Standard +0.8
In this question you must show detailed reasoning. You are given that \(\alpha\), \(\beta\) and \(\gamma\) are the roots of the equation \(5x^3 - 2x^2 + 3x + 1 = 0\).
  1. Find the value of \(\alpha^2\beta^2 + \beta^2\gamma^2 + \gamma^2\alpha^2\). [5]
  2. Find a cubic equation whose roots are \(\alpha^2\), \(\beta^2\) and \(\gamma^2\) giving your answer in the form \(ax^3 + bx^2 + cx + d = 0\) where \(a\), \(b\), \(c\) and \(d\) are integers. [4]
OCR FP1 AS 2017 Specimen Q1
3 marks Moderate -0.3
**In this question you must show detailed reasoning.** The equation \(x^2 + 2x + 5 = 0\) has roots \(\alpha\) and \(\beta\). The equation \(x^2 + px + q = 0\) has roots \(\alpha^2\) and \(\beta^2\). Find the values of \(p\) and \(q\). [3]
Pre-U Pre-U 9795/1 2015 June Q11
13 marks Challenging +1.3
  1. The cubic equation \(x^3 + 2x^2 + 3x - 4 = 0\) has roots \(p\), \(q\) and \(r\). A second cubic equation has roots \(qr\), \(rp\) and \(pq\). Show how the substitution \(y = \frac{4}{x}\) can be used to determine this second equation. Hence, or otherwise, find this equation in the form \(y^3 + ay^2 + by + c = 0\). [6]
  2. The cubic equation \(x^3 - 4x^2 + 5x - 4 = 0\) has roots \(\alpha\), \(\beta\) and \(\gamma\). You are given that \(\alpha\) is real and positive, and that \(\beta\) and \(\gamma\) are complex.
    1. Describe the relationship between \(\beta\) and \(\gamma\). [1]
    2. Explain why \(|\beta| = \frac{2}{\sqrt{\alpha}}\). [2]
    3. Verify that \(\alpha = 2.70\) correct to 3 significant figures, and deduce that \(\text{Re}(\beta) = 0.65\) correct to 2 significant figures. [4]
Pre-U Pre-U 9795/1 2018 June Q6
8 marks Challenging +1.8
The cubic equation \(4x^3 - 12x^2 + 9x - 16 = 0\) has roots \(r_1\), \(r_2\) and \(r_3\). A second cubic equation, with integer coefficients, has roots \(R_1 = \frac{r_2 + r_3}{r_1}\), \(R_2 = \frac{r_3 + r_1}{r_2}\) and \(R_3 = \frac{r_1 + r_2}{r_3}\).
  1. Show that \(1 + R_1 = \frac{3}{r_1}\) and write down the corresponding results for the other roots. [2]
  2. Using a substitution based on this result, or otherwise, find this second cubic equation. [6]