Question

if x+1/x=7 then find x³+1/x³​

Answer 1

Answer:

Step-by-step explanation:

Hi ,

It is given that ,

x + 1/x = 7 -----( 1 )

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We know the algebraic identity,

a³ + b³ + 3ab ( a + b ) = ( a + b )³

Or

a³ + b³ = ( a + b )³ - 3ab( a + b )

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x³ + 1/x³ = (x + 1/x )³- 3 × x ×1/x(x + 1/x )

= ( x + 1/x )³ - 3( x + 1/x )

= 7³ - 3 × 7

= 7( 7² - 3 )

= 7 ( 49 - 3 )

= 7 × 46

= 322

I hope this helps you.

: )