Answer:
Given x = 3 + 2√2
(3+2√2)^2= 17+12√2
⇒ x^2 = 17 + 12√2
⇒ 1/x2 = 1/(17 + 12√2)
On rationalizing the denominator we get
1/x2 = (17 – 12√2)
∴ (x2 +1/x2) =
(17 + 12√2) + (17 – 12√2)
= 34
(3+2√2)² + 1/(3+2√2)²
9 + 8 + 12√2 + 1
____
9 + 8 + 12√2
17 + 12√2 + 1
______
17 + 12√2
289 + 288 + 408√2 + 1
____________________
17 + 2√2
578 + 408√2
__________
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Answers & Comments
Answer:
Given x = 3 + 2√2
(3+2√2)^2= 17+12√2
⇒ x^2 = 17 + 12√2
⇒ 1/x2 = 1/(17 + 12√2)
On rationalizing the denominator we get
1/x2 = (17 – 12√2)
∴ (x2 +1/x2) =
(17 + 12√2) + (17 – 12√2)
= 34
Verified answer
Answer:
(3+2√2)² + 1/(3+2√2)²
9 + 8 + 12√2 + 1
____
9 + 8 + 12√2
17 + 12√2 + 1
______
17 + 12√2
289 + 288 + 408√2 + 1
____________________
17 + 2√2
578 + 408√2
__________
17 + 12√2