Question

if x = ( 3+√8) find value of x^3+ 1/x^3

Answer 1

Given that..

x=3+8–√…(1)x=3+8…(1)

⇒1x=3−8√(3)2−(8√)2⇒1x=3−8(3)2−(8)2

⇒1x=3−8–√….(2)⇒1x=3−8….(2)

Now adding (1) & (2) we get…

x+1x=(3+8–√)+(3−8–√)x+1x=(3+8)+(3−8)

⇒x+1x=6⇒x+1x=6

Now,

x2+1x2x2+1x2

=(x+1x)2–2.x1x=(x+1x)2–2.x1x

=62–2=62–2

=36–2=36–2

=34=34. (Ans).

Answer 2

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