using identity (a+b)^2 = a^2 + 2ab + b^2 find the value of x^2 + 1/x^2 if x+1/x = 3
Answers
Answered by
1
Step-by-step explanation:
x+1/x =3
(x+1/'x)^2=9
x^2 +1/x^2 +2=9
x^2 +1/x^2 =9
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Answered by
0
Answer:
x² + 1/x² = 7
Note:
★ (a + b)² = a² + 2ab + b²
★ (a - b)² = a² - 2ab + b²
★ a² - b² = (a + b)(a - b)
★ (a + b)³ = a³ + b³ + 3ab(a + b)
★ (a - b)³ = a³ + b³ - 3ab(a - b)
★ a³ + b³ = (a + b)(a² - ab + b²)
★ a³ - b³ = (a - b)(a² + ab + b²)
Solution:
Given : x + 1/x = 3
To find : x² + 1/x² = ?
We have ;
x + 1/x = 3
Now,
Squaring both sides , we get ;
=> (x + 1/x)² = 3²
=> x² + 2•x•(1/x) + (1/x)² = 9
=> x² + 2 + 1/x² = 9
=> x² + 1/x² = 9 - 2
=> x² + 1/x² = 7
Hence,
The required answer is 7 .
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