Question

If x-1/x= 5, then the value of x3 - 1/x3
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Answer 1

Answer:

x³-1/x³=140

Step-by-step explanation:

x-1/x=5

(x-1/x)³=5³

x³-1/x³-3.x.1/x(x-1/x)= 125

x³-1/x³ = 125+3.5

x³-1/x³= 125+15

x³-1/x³= 140

Answer 2

Answer:

140

Step-by-step explanation:

$\rm \: x - \frac{1}{x} = 5 \\ \rm \: Cubing \: on \: both \: sides \\ \rm \longrightarrow\rm\bigg(x - \frac{1}{x } \bigg) ^{3} = (5) ^{3} \\ \rm \longrightarrow\rm x {}^{3} - \frac{1}{ {x}^{3} } - 3 \bigg(x - \frac{1}{x} \bigg) = 125 \\ \rm \longrightarrow \: {x}^{3} - \frac{1}{ {x}^{3} } - 3(5) = 125 \\ \rm \longrightarrow {x}^{3} - \frac{1}{ {x}^{3} } - 15 = 125 \\ \rm \longrightarrow {x}^{3} - \frac{1}{ {x}^{3} } = 125 + 15 \\ \rm \longrightarrow \pink{ {x}^{3} - \frac{1}{ {x}^{3} } = 140}$