1.

where a and b are natural number find (a + b).​

Answer»

\begin{gathered}\Large{\bold{{\underline{Formula \: Used - }}}}  \end{gathered}

\boxed{ \sf \:  {(x + y)}^{2}  =  {x}^{2}  +  {y}^{2}  + 2xy}

\boxed{ \sf \:  {(x - y)}^{2}  =  {x}^{2}  +  {y}^{2}  - 2xy}

\large\underline{\sf{Solution-}}

CONSIDER,

\sf \: 2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{13 +  \sqrt{48} } } } \bigg)

\sf \:  =  \: 2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{12 + 1 +  \sqrt{2 \times 2 \times 4 \times 3} } } } \bigg)

\sf \: =  \:  2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{ {( \sqrt{12)} }^{2}  + {(1)}^{2} + 2  \sqrt{12} } } } \bigg)

\sf \:  = 2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{ {\bigg( \sqrt{12}  + 1 \bigg) }^{2}  } } } \bigg)

\: \:  \:  \:  \:  \:  \:  \:  \:  \:  \:   \:  \:  \: \boxed{ \sf  \because \:  {(x + y)}^{2}  =  {x}^{2}  +  {y}^{2} + 2xy }

\sf \: =  2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{12}  - 1 } } \bigg)

\sf \: =  2\bigg(  \sqrt{3 +  \sqrt{4 -  \sqrt{12}  } } \bigg)

\sf \: =  2\bigg(  \sqrt{3 +  \sqrt{3 + 1 -  \sqrt{2 \times 2 \times 3}} } \bigg)

\sf \: =  2\bigg(  \sqrt{3 +  \sqrt{ {( \sqrt{3)} }^{2}  +  {(1)}^{2}  - 2 \sqrt{3}} } \bigg)

\sf \:  =  \: 2\bigg(  \sqrt{3 +  \sqrt{ {( \sqrt{3}  -  1) }^{2} } } \bigg)

\sf \:  =  \: 2 \sqrt{\bigg(3 +  \sqrt{3} - 1  \bigg) }

\sf \:  =  \: 2 \sqrt{\bigg(2 +  \sqrt{3}  \bigg) }

\sf \:  =  \:  2\sqrt{ \bigg( \dfrac{3}{2}  + \dfrac{1}{2}  +  \sqrt{3} \times \dfrac{2}{ \sqrt{2} \times  \sqrt{2}  }  \bigg) }

\sf \:  =  \: 2 \sqrt{\bigg( {\bigg(\dfrac{ \sqrt{3} }{ \sqrt{2} }  \bigg) }^{2} +  {\bigg(\dfrac{1}{ \sqrt{2} }  \bigg) }^{2}   + 2 \times \dfrac{ \sqrt{3} }{ \sqrt{2} }  \times \dfrac{1}{ \sqrt{2} }  \bigg) }

\sf \:  =  \: 2 \sqrt{ {\bigg(\dfrac{ \sqrt{3} }{ \sqrt{2} }  + \dfrac{1}{ \sqrt{2} }  \bigg) }^{2} }

\sf \:  =  \: 2\bigg( \dfrac{ \sqrt{3} }{ \sqrt{2} }  + \dfrac{1}{ \sqrt{2} } \bigg)

\sf \:  =  \:  \sqrt{2}  \times  \sqrt{2}  \times \bigg(\dfrac{ \sqrt{3} }{ \sqrt{2} }  + \dfrac{1}{ \sqrt{2} }  \bigg)

\sf \:  =  \:  \sqrt{6}  +  \sqrt{2}

So,

\rm :\implies\:\sf \: 2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{13 +  \sqrt{48} } } } \bigg)  =  \sqrt{6}  +  \sqrt{2}

As it is GIVEN that,

\sf \: 2\bigg(  \sqrt{3 +  \sqrt{5 -  \sqrt{13 +  \sqrt{48} } } } \bigg)  =  \sqrt{a}  +  \sqrt{b}

So,

On COMPARING we GET,

\rm :\implies\: \sqrt{a}  +  \sqrt{b}  =  \sqrt{6}  +  \sqrt{2}

\bf\implies \:a = 6 \:  and \:  b = 2 \:  \: or \: a = 2 \: and \: b = 6

So,

\bf\implies \:a + b = 2 + 6 = 8

\overbrace{ \underline { \boxed { \rm \therefore \: The \: value \: of \: a  \: + \:  b  \: = \:  8 }}}



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