if x plus one upon x is equal to 3 find the value of x cube + 1 upon X cube
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x+1/x = 3 .....(1)
Cubing both sides
(X+1/x)^3 = 27
we know, (a+b)^3 = a^3 + b^3 + 3a^2b + 3ab^2
x^3 + 1/x^3 + 3x^2*1/x + 3x*1/x^3 = 27
x^3 + 1/x^3 + 3x + 3/x = 27
x^3 + 1/x^3 + 3(x+1/x) = 27
using (1)
x^3 + 1/x^3 + 3(3) = 27
x^3 + 1/x^3 = 27 - 9 = 18
Cubing both sides
(X+1/x)^3 = 27
we know, (a+b)^3 = a^3 + b^3 + 3a^2b + 3ab^2
x^3 + 1/x^3 + 3x^2*1/x + 3x*1/x^3 = 27
x^3 + 1/x^3 + 3x + 3/x = 27
x^3 + 1/x^3 + 3(x+1/x) = 27
using (1)
x^3 + 1/x^3 + 3(3) = 27
x^3 + 1/x^3 = 27 - 9 = 18
Alabhya1273:
sorry put 27 in place of 9
u ll get right answer
answer will be 18
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