If x2 - 6x - 1 = 0, then find the value of x2 + - 8.
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 30.
x² - 6x - 1=0
⇒ x² - 1 = 6x
dividing by x on both sides we get,
⇒ x - 1/x = 6
squaring both sides we get
⇒ (x - 1/x)² = 36
⇒ x² + 1/x² - 2 = 36
⇒ x² + 1/x² = 38
x² + 1/x² - 8
38 - 8 = 30