Math, asked by shailendragupta, 1 year ago

if x+1/x=6,find x^5+1/x^5

Answers

Answered by kishika
2
x+1/x=6 ……………..(1)

Squaring both sides

x^2+1/x^2+2=36

x^2+1/x^2=34 ………..(2)

On cubing eq.(1) both sides

x^3+1/x^3+3.x1/x.(x+1/x)=216

x^3+1/x^3+3×6=216

x^3+1/x^3=216–18

x^3+1/x^3=198………………(3)

Multiply eq.(2) & (3)

(x^2+1/x^2)×(x^3+1/x^3)=34×198

x^5+x+1/x+1/x^5=6732

x^5+6+1/x^5=6732

x^5+1/x^5=6732–6=6726 , Answer

Answered by rakeshmohata
14
Hope u like my process
=====================
 =  > x +  \frac{1}{x}  = 6 \\  \\  \underline{ \bf \:  \: squaring \:  \: both \:  \: sides \:  \: } \\  \\  =  >  {x}^{2}  +  \frac{1}{ {x}^{2} }  + 2x \frac{1}{x}  =  {6}^{2}  \\  \\  =  >  {x}^{2}  +  \frac{1}{ {x}^{2} }  + 2 = 36 \\  \\  =  >   \boxed{ \bf {x}^{2}  +  \frac{1}{ {x}^{2} } = 36 - 2 =  \underline{ \green{34} }} \\  \\ now \\  \\ again \:  \: x +  \frac{1}{x}  = 6 \\  \\  \underline{ \bf \:  \: cubing \:  \: both \:  \: sides \:  \: } \\  \\   =  > {x}^{3}  +  \frac{1}{ {x}^{3} }  + 3 {x}\frac{1}{x} (x +  \frac{1}{ {x} })  =  {6}^{3}  \\  \\ =   >  {x}^{3}  +  \frac{1}{ {x}^{3} }  + 3 \times 1 \times 6 = 216 \\  \\  =  >  \boxed{ \bf \:  {x}^{3} +  \frac{1}{ {x}^{3} } = 216 - 18 = \underline{  \green{198}}  }
Now..

Multiplying both equation we get..

 =  > ( {x}^{2}  +  \frac{1}{ {x}^{2} } )( {x}^{3}  +  \frac{1}{ {x}^{3} } ) = 34 \times 198 \\  \\  =  >  {x}^{2 + 3}   +  \frac{1}{ {x}^{2 + 3} }  +  {x}^{3 - 2}  +  \frac{1}{ {x}^{3 - 2} }  = 6732 \\  \\  =  >  {x}^{5}  +  \frac{1}{ {x}^{5} }   + (x +  \frac{1}{x} )= 6732 \\  \\  =  >  \boxed{ \bf \:  {x}^{5}  +  \frac{1}{ {x}^{5} } = 6732 - 6 =  \underline{ \orange{6726}} }
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