a + 1/a=√3 then a^3 + 1/a^3=
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We need to find a² + 1/a² in order to find a³ + 1/a³
a + 1/a = √3
Squaring both the sides,
(a + 1/a)² = (√3)²
=> a² + 1/a² + 2 = 3
=> a² + 1/a²= 3 - 2
=> a² + 1/a² = 1
Now, we know that,
a³ + b³ = (a + b)(a² + b² - ab)
Here a = a and b = 1/a
so, a³ + 1/a³ = (a + 1/a)[a² + 1/a² - a(1/a)]
a³ + 1/a³ = (√3)(1 - 1)
(since, a + 1/a = √3, a × 1/a = 1 and a² + 1/a² = 1 as derived above)
=> a³ + 1/a³ = (√3)(0)
=> a³ + 1/a³ = 0
Hope it helps dear friend ☺️✌️✌️
a + 1/a = √3
Squaring both the sides,
(a + 1/a)² = (√3)²
=> a² + 1/a² + 2 = 3
=> a² + 1/a²= 3 - 2
=> a² + 1/a² = 1
Now, we know that,
a³ + b³ = (a + b)(a² + b² - ab)
Here a = a and b = 1/a
so, a³ + 1/a³ = (a + 1/a)[a² + 1/a² - a(1/a)]
a³ + 1/a³ = (√3)(1 - 1)
(since, a + 1/a = √3, a × 1/a = 1 and a² + 1/a² = 1 as derived above)
=> a³ + 1/a³ = (√3)(0)
=> a³ + 1/a³ = 0
Hope it helps dear friend ☺️✌️✌️
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21
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