Question

if x-1/x=4 find the value of x^3-1/x^3

Answer 1

if x-1/x=4 find the value of x^3-1/x^3

Answer 2

x - 1/x =4
by taking cube both side , we get

(x - 1/x )^3 = (4)^3

x ^3 -1/x^3 - 3(x^2)(1/ x) + 3(x)(1/x)^2=64

x^3 - 1/x^3 - 3x + 3 (1 /x )=64

x^3 - 1/ x^3 - 3( x - 1/ x ) = 64

x^3 - 1/x^3 - 3( 4) = 64

x^3 - 1/x^3 - 12 = 64

x^3 - 1/x^3 =64 + 12

x^3 - 1/x^3 =76
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Your Answer : x^3 - 1/x^3 = 76
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