If the roots of the equation 8x2+6x+a=0 are of the form α and α2, Then the value of a is
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a
1, −27
b
−1, 27
c
−1, −27
d
1, 27
answer is A.
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Detailed Solution
The given equation is 8x2+6x+a=0 The given roots are α and α2 Sum of the roots : α+α2= 34 Product of the roots : α×α2= a8 α+α2= 34 cubing on both sides, we get α3+α6+3αα2(α+α2) = 2764 ⇒ α3 +(α3)2 +3α3(α+α2)= 2764 ⇒ a8 +a264+3a8 (34)= 2764 (∵ α3= a8) ⇒ a2+26a−27=0 ⇒a2+27a−a−27=0 ⇒(a−1)(a+27)=0 ∴ a=1,−27