Question

x+ 1 upon x = 2 then find x^3+ 1 upon x^3=?

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Answer 1

Answer:

the answer is as follows

Step-by-step explanation:

[math]x + \dfrac{1}{x} = 3[/math]

[math](x + \dfrac{1}{x})^3 = 3^3[/math]

[math]x^3 + 3.x^2.\dfrac{1}{x} + 3.x.\dfrac{1}{x^2} + \dfrac{1}{x^3} = 27[/math]

[math](x^3 + \dfrac{1}{x^3}) + 3.x^2.\dfrac{1}{x} + 3.x.\dfrac{1}{x^2} = 27[/math]

[math]x^3 + \dfrac{1}{x^3} + (3x + \dfrac{3}{x}) = 27[/math]

[math]x^3 + \dfrac{1}{x^3} + 3(x + \dfrac{1}{x}) = 27[/math]

[math]x^3 + \dfrac{1}{x^3} + 3 × 3 = 27[/math]

[math]x^3 + \dfrac{1}{x^3} + 9 = 27[/math]

[math]x^3 + \dfrac{1}{x^3} = 18[/math]

Therefore the answer is 18

Answer 2

Answer:

Step-by-step explanation:

x+1/x =3

square both the sides-

x²+1/x² +2 ×x× 1/x =3²

x²+1/x² +2=9

x²+1/x² =7

Now to find value of x³+1/x³ first expand it

x³+1/x³ = (x+1/x) (x²+1/x² -1)

=(3)(7–1)

=3×6

x³+1/x³ =18