what is the answer of this equation
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Correct Question is to find (x³ + 1/x³) ??
Solution:
x - 1/x = 5
You might be knowing the formula:
(a + b)³ = a³ + b³ + 3ab(a + b)
So, a³ + b³ = (a + b)³ - 3ab
Now, assume a = x, b = 1/x
Thus the formula changes to:
(x)³ + (1/x)³ = (x + 1/x)³ - 3(x)(1/x)
x³ + 1/x³ = (x + 1/x)³ - 3(1)
x³ + 1/x³ = (5)² + 3 = 25 - 3
x³ + 1/x³ = 22
{these questions are very easy, you just have to remember the Basic Formulas of a & b.
Like:
(a ± b)² = a² + b² ± 2ab
(a ± b)³ = a³ ± b³ ± 3ab(a ± b)
etc...
if you still have any doubt, feel free to comment.}
:)
Thankyou!!!
Correct Question is to find (x³ + 1/x³) ??
Solution:
x - 1/x = 5
You might be knowing the formula:
(a + b)³ = a³ + b³ + 3ab(a + b)
So, a³ + b³ = (a + b)³ - 3ab
Now, assume a = x, b = 1/x
Thus the formula changes to:
(x)³ + (1/x)³ = (x + 1/x)³ - 3(x)(1/x)
x³ + 1/x³ = (x + 1/x)³ - 3(1)
x³ + 1/x³ = (5)² + 3 = 25 - 3
x³ + 1/x³ = 22
{these questions are very easy, you just have to remember the Basic Formulas of a & b.
Like:
(a ± b)² = a² + b² ± 2ab
(a ± b)³ = a³ ± b³ ± 3ab(a ± b)
etc...
if you still have any doubt, feel free to comment.}
:)
Thankyou!!!
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