Question
Download Solution PDFThe sum of squares of all the roots of the equation:
\((x + \frac{1}{x})^2 - 4 = \frac{3}{2}(x - \frac{1}{x}), x \neq 0\) is:
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFGiven:
The equation is (x + 1/x)2 - 4 = 3/2(x - 1/x), x ≠ 0
Formula used:
(a + b)2 = a2 + b2 + 2ab
(a - b)2 = a2 + b2 - 2ab
We know that (x + 1/x)2 = x2 + 1/x2 + 2
And (x - 1/x)2 = x2 + 1/x2 - 2
Also, (x + 1/x)2 - (x - 1/x)2 = 4
Calculation:
Let y = x - 1/x.
Then (x + 1/x)2 = (x - 1/x)2 + 4 = y2 + 4.
Substitute these into the given equation:
(y2 + 4) - 4 = 3/2 y
⇒ y2 = 3/2 y
⇒ 2y2 = 3y
⇒ 2y2 - 3y = 0
⇒ y(2y - 3) = 0
This gives two possible values for y:
1. y = 0
2. 2y - 3 = 0 ⇒ y = 3/2
Case 1: x - 1/x = 0
⇒ (x2 - 1)/x = 0
⇒ x2 - 1 = 0
⇒ x2 = 1
⇒ x = ± 1
So, the roots are 1 and -1.
Case 2: x - 1/x = 3/2
⇒ (x2 - 1)/x = 3/2
⇒ 2(x2 - 1) = 3x
⇒ 2x2 - 2 = 3x
⇒ 2x2 - 3x - 2 = 0
⇒ 2x2 - 4x + x - 2 = 0
⇒ 2x(x - 2) + 1(x - 2) = 0
⇒ (2x + 1)(x - 2) = 0
⇒ x - 2 = 0 ⇒ x = 2
⇒ 2x + 1 = 0 ⇒ x = -1/2
The roots of the equation are 1, -1, 2, and -1/2.
Now, calculate the sum of the squares of all the roots:
Sum of squares = (1)2 + (-1)2 + (2)2 + (-1/2)2
= 1 + 1 + 4 + 1/4
= 6 + 1/4
= (24 + 1)/4
= 25/4 = \(6\frac{1}{4}\)
∴ The correct answer is option 3.
Last updated on Jul 2, 2025
-> CBSE Superintendent 2025 Skill Test Hall Ticket has been released on the official website.
-> The CBSE Superintendent 2025 Skill Test Notice has been released which will be conducted on 5th July 2025.
-> The Tier-I Exam was conducted on 20th April 2025.
-> Eligible candidates had submitted their applications online between January 2nd and 31st, 2025.
-> The selection process includes written examination and document verification.
-> This position entails managing administrative and operational duties within the board, requiring excellent organizational skills to ensure the seamless execution of academic and administrative functions.