If x= 5-2 √6 Then find the value of x² + 1/x²
Answers
ANSWER :–
▪︎ x² + 1/x² = 98
EXPLANATION :–
GIVEN :–
▪︎ Value of x is 5 - 2√6
TO FIND :–
Value of x² + 1/x² = ?
SOLUTION :–
▪︎ We know that –
⇨ (a + b)² = a² + b² + 2ab
▪︎ Now put a = x and b = 1/x –
⇨ (x + 1/x)² = x² + 1/x² + 2(x)(1/x)
⇨ (x + 1/x)² = x² + 1/x² + 2
⇨ x² + 1/x² = (x + 1/x)² - 2 —————eq.(1)
▪︎ Now let's find (1/x) –
⇒ 1/x = 1/(5 - 2√6)
⇒ 1/x = [1/(5 - 2√6)][(5 + 2√6)/(5 + 2√6)]
⇒ 1/x = (5 + 2√6)/(25 - 24)
⇒ 1/x = 5 + 2√6
▪︎ Now put the value of x and 1/x in eq.(1) –
⇒ x² + 1/x² = (5 - 2√6 + 5 + 2√6)² - 2
⇒ x² + 1/x² = (10)² - 2
⇒ x² + 1/x² = 100 - 2
⇒ x² + 1/x² = 98
Answer:
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