Question
Download Solution PDFIf x − \(\rm\frac{1}{x}\) = 3, the value of x3 − \(\rm\frac{1}{x^3}\) is
This question was previously asked in
Bihar STET Paper I: Mathematics (Held In 2019 - Shift 1)
Answer (Detailed Solution Below)
Option 1 : 36
Free Tests
View all Free tests >
Bihar STET Paper 1 Mathematics Full Test 1
13.9 K Users
150 Questions
150 Marks
150 Mins
Detailed Solution
Download Solution PDFGiven:
x - 1/x = 3
Concept used:
a3 - b3 = (a - b)3 + 3ab(a - b)
Calculation:
x3 - 1/x3 = (x - 1/x)3 + 3 × x × 1/x × (x - 1/x)
⇒ (x - 1/x)3 + 3(x - 1/x)
⇒ (3)3 + 3 × (3)
⇒ 27 + 9 = 36
∴ The value of x3 - 1/x3 is 36.
Alternate Method If x - 1/x = a, then x3 - 1/x3 = a3 + 3a
Here a = 3
x - 1/x3 = 33 + 3 × 3
= 27 + 9
= 36
Last updated on Jan 29, 2025
-> The Bihar STET 2025 Notification will be released soon.
-> The written exam will consist of Paper-I and Paper-II of 150 marks each.
-> The candidates should go through the Bihar STET selection process to have an idea of the selection procedure in detail.
-> For revision and practice for the exam, solve Bihar STET Previous Year Papers.