>
Exams
>
Mathematics
>
Sequence and series
>
if and are the roots of the equation x2 x 1 0 then
Question:
If α and β are the roots of the equation x
2
+ x + 1 = 0, then the equation whose roots are α
19
and β
7
is
WBJEE
Updated On:
Apr 23, 2024
(A) x
2
– x – 1 = 0
(B) x
2
– x + 1 = 0
(C) x
2
+ x – 1= 0
(D) x
2
+ x + 1 = 0
Hide Solution
Verified By Collegedunia
The Correct Option is
D
Solution and Explanation
Explanation:
α
and
β
are the roots of
x
2
+
x
+
1
=
0
α
=
ω
β
=
ω
2
α
19
=
ω
β
7
=
ω
2
x
2
−
(
α
19
+
β
′
)
x
+
α
19
β
7
=
0
Thou,
x
2
−
(
ω
+
ω
2
)
x
+
ω
⋅
ω
2
=
0
x
2
+
x
+
1
=
0
Download Solution in PDF
Was this answer helpful?
0
0
Top Questions on Sequence and series
The sum of the series \[ \frac{1}{1 - 3 \cdot 1^2 + 1^4} + \frac{2}{1 - 3 \cdot 2^2 + 2^4} + \frac{3}{1 - 3 \cdot 3^2 + 3^4} + \ldots \text{ up to 10 terms} \] is
JEE Main - 2024
Mathematics
Sequence and series
View Solution
Let 2nd, 8th, and 44th terms of a non-constant A.P. be respectively the 1st, 2nd, and 3rd terms of a G.P. If the first term of A.P. is 1, then the sum of the first 20 terms is equal to
JEE Main - 2024
Mathematics
Sequence and series
View Solution
If \( a_1, a_2, \dots, a_n \) are in A.P. with common difference \( \theta \), then the sum of the series:
\[ \sec a_1 \sec a_2 + \sec a_2 \sec a_3 + \dots + \sec a_{n-1} \sec a_n = k (\tan a_n - \tan a_1), \]
where \( k = ? \)
WBJEE - 2024
Mathematics
Sequence and series
View Solution
Given an A.P. and a G.P. with positive terms, with the first and second terms of the progressions being equal. If \(a_n\) and \(b_n\) be the \(n\)-th term of A.P. and G.P. respectively, then:
WBJEE - 2024
Mathematics
Sequence and series
View Solution
If for the series \(a_1, a_2, a_3, \ldots\), etc., \(a_{n+1} - a_n\) bears a constant ratio with \(a_n + a_{n+1}\), then \(a_1, a_2, a_3, \ldots\) are in:
WBJEE - 2024
Mathematics
Sequence and series
View Solution
View More Questions
Questions Asked in WBJEE exam
A satellite of mass \(m\) rotates round the earth in a circular orbit of radius \(R\). If the angular momentum of the satellite is \(J\), then its kinetic energy (\(K\)) and the total energy (\(E\)) of the satellite are:
WBJEE - 2024
Gravitation
View Solution
A 2V cell is connected across the points A and B as shown in the figure. Assume that the resistance of each diode is zero in forward bias and infinity in reverse bias. The current supplied by the cell is:
WBJEE - 2024
Current electricity
View Solution
Consider a circuit where a cell of emf \( E_0 \) and internal resistance \( r \) is connected across the terminal A and B as shown in the figure. The value of \( R \) for which the power generated in the circuit is maximum, is given by:
WBJEE - 2024
Current electricity
View Solution
The variation of impedance Z of a series LCR circuit with frequency of the source is shown in the figure. Which of the following statement(s) is/are true?
WBJEE - 2024
Alternating current
View Solution
In a series LCR circuit, the rms voltage across the resistor and the capacitor are \(30 \, \text{V}\) and \(90 \, \text{V}\) respectively. If the applied voltage is \(50\sqrt{2}\sin\omega t\), then the peak voltage across the inductor is:
WBJEE - 2024
Alternating current
View Solution
View More Questions