if α and β are the zeroes of 3x²-2x-21,find the value of α³ + β³
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Solution:
》given eq is :- 3x²-2x-21
》α+ β = -b/a = 2/3
》αβ = c/a = -21/3 = -7
_______________________
》α²+ β²=(α + β)²-2αβ
》α²+ β²=(2/3)²-2×(-7) =4/9+14=(56+9)/126
》= 65/126
》α³ + β³ = (α + β)(α²+ β²-αβ)
》α³ + β³ = (2/3)×(65/126-2/3)
》= 2/3×(65-84)/126
》= -38/378
》α³ + β³ = -19/189 ans
》given eq is :- 3x²-2x-21
》α+ β = -b/a = 2/3
》αβ = c/a = -21/3 = -7
_______________________
》α²+ β²=(α + β)²-2αβ
》α²+ β²=(2/3)²-2×(-7) =4/9+14=(56+9)/126
》= 65/126
》α³ + β³ = (α + β)(α²+ β²-αβ)
》α³ + β³ = (2/3)×(65/126-2/3)
》= 2/3×(65-84)/126
》= -38/378
》α³ + β³ = -19/189 ans
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