Question

if 4-x=1/x,find value of x cube + 1/ x cube​

Answer 1

4x-x2

x2=4x

x=4

now,

x3+1/x=(4) 3+1/4

=257/4

=64.25

Answer 2

Answer:

Given,

$x + \frac{1}{x} = 4$

So, now

${x}^{3} + \frac{1}{ {x}^{3} } = (x + \frac{1}{x} ) {}^{3} - 3 \times x \times \frac{1}{x} (x + \frac{1}{x} ) = {4}^{3} - 3 \times 4 = 64 - 12 = 52$