The equation x⁴ - 2x³ − 1 = 0 has roots α, β, γ, δ.
- (a)Find a quartic equation whose roots are α³, β³, γ³, δ³ and state the value of α³ + β³ + γ³ + δ³.[4]
- (b)Find the value of 1/α³ + 1/β³ + 1/γ³ + 1/δ³.[3]
- (c)Find the value of α⁴ + β⁴ + γ⁴ + δ⁴.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2021). The mark or mark type is shown in brackets.
- [B1] Correct substitution.
- [M1] Obtains an equation not involving radicals.
- [A1]
- [B1 FT]
- [M1 A1 FT] Relates 1/α³ + 1/β³ + 1/γ³ + 1/δ³ to coefficients.
- [A1]
- [M1] Uses original equation.
- [A1]
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