Solve p(algebraic transform) = 0

Questions where you solve p((y+c)^r) = 0 for rational exponents r (like (y+3)^(1/2) or (y-2)^2) by first solving p(x) = 0, then solving algebraic equations involving powers and roots.

7 questions

CAIE P3 2012 June Q3
3 The polynomial \(\mathrm { p } ( x )\) is defined by $$\mathrm { p } ( x ) = x ^ { 3 } - 3 a x + 4 a$$ where \(a\) is a constant.
  1. Given that \(( x - 2 )\) is a factor of \(\mathrm { p } ( x )\), find the value of \(a\).
  2. When \(a\) has this value,
    (a) factorise \(\mathrm { p } ( x )\) completely,
    (b) find all the roots of the equation \(\mathrm { p } \left( x ^ { 2 } \right) = 0\).
Edexcel P1 2020 January Q5
5. (a) Find, using algebra, all solutions of $$20 x ^ { 3 } - 50 x ^ { 2 } - 30 x = 0$$ (b) Hence find all real solutions of $$20 ( y + 3 ) ^ { \frac { 3 } { 2 } } - 50 ( y + 3 ) - 30 ( y + 3 ) ^ { \frac { 1 } { 2 } } = 0$$
Edexcel P1 2019 June Q5
  1. (a) Find, using algebra, all real solutions of
$$2 x ^ { 3 } + 3 x ^ { 2 } - 35 x = 0$$ (b) Hence find all real solutions of $$2 ( y - 5 ) ^ { 6 } + 3 ( y - 5 ) ^ { 4 } - 35 ( y - 5 ) ^ { 2 } = 0$$
Edexcel P1 2021 June Q2
2. In this question you must show all stages of your working. Solutions relying on calculator technology are not acceptable. $$f ( x ) = a x ^ { 3 } + ( 6 a + 8 ) x ^ { 2 } - a ^ { 2 } x$$ where \(a\) is a positive constant. Given \(\mathrm { f } ( - 1 ) = 32\)
    1. show that the only possible value for \(a\) is 3
    2. Using \(a = 3\) solve the equation $$\mathrm { f } ( x ) = 0$$
  1. Hence find all real solutions of
    1. \(3 y + 26 y ^ { \frac { 2 } { 3 } } - 9 y ^ { \frac { 1 } { 3 } } = 0\)
    2. \(3 \left( 9 ^ { 3 z } \right) + 26 \left( 9 ^ { 2 z } \right) - 9 \left( 9 ^ { z } \right) = 0\)
Edexcel P1 2022 October Q4
  1. In this question you must show detailed reasoning. Solutions relying on calculator technology are not acceptable.
$$f ( x ) = x ^ { 2 } ( 2 x + 1 ) - 15 x$$
  1. Solve $$\mathrm { f } ( x ) = 0$$
  2. Hence solve $$y ^ { \frac { 4 } { 3 } } \left( 2 y ^ { \frac { 2 } { 3 } } + 1 \right) - 15 y ^ { \frac { 2 } { 3 } } = 0 \quad y > 0$$ giving your answer in simplified surd form.
Edexcel AS Paper 1 2021 November Q6
  1. In this question you should show all stages of your working.
Solutions relying on calculator technology are not acceptable.
  1. Using algebra, find all solutions of the equation $$3 x ^ { 3 } - 17 x ^ { 2 } - 6 x = 0$$
  2. Hence find all real solutions of $$3 ( y - 2 ) ^ { 6 } - 17 ( y - 2 ) ^ { 4 } - 6 ( y - 2 ) ^ { 2 } = 0$$
SPS SPS SM 2022 October Q7
7. In this question you should show all stages of your working. Solutions relying on calculator technology are not acceptable.
  1. Using algebra, find all solutions of the equation $$3 x ^ { 3 } - 17 x ^ { 2 } - 6 x = 0$$
  2. Hence find all real solutions of $$3 ( y - 2 ) ^ { 6 } - 17 ( y - 2 ) ^ { 4 } - 6 ( y - 2 ) ^ { 2 } = 0$$ [BLANK PAGE]