Math, asked by RehanAhmadXLX, 1 year ago

Page : 1.4
Find the value of (a⁴ + b⁴) if a =   \frac{ \sqrt{3} + \sqrt{2} }{ \sqrt{3}-  \sqrt{2}  }  \:  and \\ b = \frac{ \sqrt{3} - \sqrt{2} }{ \sqrt{3}+  \sqrt{2}  }

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Answered by Swarup1998
12
The answer is given below :

Now,
a =  \frac{ \sqrt{3} +  \sqrt{2}  }{ \sqrt{3}  -  \sqrt{2} }  \\  \\  =  \frac{ \sqrt{3} +  \sqrt{2}  }{ \sqrt{3}  -  \sqrt{2} }  \times   \frac{ \sqrt{3} +  \sqrt{2}  }{ \sqrt{3}  +  \sqrt{2} }  \\  \\  =  \frac{ {( \sqrt{3} +  \sqrt{2})  }^{2}  }{3 -2 }  \\  \\  =  \frac{3 + 2  \sqrt{6}  + 2}{1}  \\   \\ = 5 + 2 \sqrt{6}

Again,

b =  \frac{ \sqrt{3}  - \sqrt{2}  }{ \sqrt{3}   +  \sqrt{2} }  \\  \\  =  \frac{ \sqrt{3}   -  \sqrt{2}  }{ \sqrt{3}      +   \sqrt{2} }  \times   \frac{ \sqrt{3}  -   \sqrt{2}  }{ \sqrt{3}   -   \sqrt{2} }  \\  \\  =  \frac{ {( \sqrt{3}  -   \sqrt{2})  }^{2}  }{3 -2 }  \\  \\  =  \frac{3  -  2  \sqrt{6}  + 2}{1}  \\   \\ = 5  - 2 \sqrt{6}

So,

 {a}^{2}  =  {(5  +  2\sqrt{6} )}^{2}  \\  \\  = 25 + 20 \sqrt{6}  + 24 \\  \\  = 49 + 20 \sqrt{6}  \\  \\ and \\  \\  {b}^{2}  =  {(5 - 2 \sqrt{6} )}^{2}  \\  \\  = 25 - 20 \sqrt{6}  + 24 \\  \\  = 49 - 20 \sqrt{6}

Now,

 {a}^{2}  +  {b}^{2}  \\  \\  = (49 + 20 \sqrt{6} ) + (49 - 20 \sqrt{6} ) \\  \\  = 98 \\  \\ and \\  \\  {a}^{2}  {b}^{2}  \\  \\  = (49 + 20 \sqrt{6} )(49 - 20 \sqrt{6} ) \\  \\  =  {49}^{2}  -  {(20  \sqrt{6} )}^{2}  \\  \\  = 2401 - 2400 \\  \\  = 1

Therefore,

 {a}^{4}  +  {b}^{4}  \\  \\  =  {( {a}^{2} +  {b}^{2} ) }^{2}  - 2 {a}^{2}  {b}^{2}  \\  \\  =  {98}^{2}  - (2 \times 1) \\  \\  = 9604 - 2 \\  \\  = 9602

Thank you for your question.

RehanAhmadXLX: Oh Yeah :-)
Anonymous: wow nice answer
Swarup1998: Thank you. (^_^)
Anonymous: nice
Swarup1998: Thanks a lot. (*_*)
IshanS: :thumbs_up:
Swarup1998: thank u ^_^
Answered by Anonymous
4
hy
here is your answer bro
====================
i dont know how to write on the formula box thats why i solved in copy
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Anonymous: what brother
Anonymous: ok
RehanAhmadXLX: Yeah ! You are right.. Sorry
Anonymous: no need of sorry brother
Anonymous: :-)
RehanAhmadXLX: :-)
Robin0071: nice gori
Anonymous: thanks
Robin0071: welcome
Swarup1998: In 22nd line, there's a mistake!
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