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मान लीजिए कि $m , n$ धनात्मक पूर्णांक $(positive\,integers)$ इस प्रकार है कि $6^m+2^{m+n} 3^m+2^n=332 . m^2+m n+n^2$ व्यंजक $(expression)$, का मान क्या होगा ?
$7$
$13$
$19$
$21$
Solution
(c)
We have,
$6^n+2^{n+n} \cdot 3^w+2^n=332$
When $m=4, LHS > RHS$
$\therefore$ Maximum value of $m=3$
When $m=3$,
$6^3+2^3 \cdot 2^n \cdot 3^w+2^n=332$
$2^n\left(8 \cdot 3^w+1\right)=332-216$
$2^n\left(8 \cdot 3^{2 v}+1\right)=116$
$2^n\left(8 \times 3^w+1\right)=4 \times 29$
$\therefore n=2$
$3^w+1=29 \Rightarrow 3^w=\frac{7}{2}$
Put $m=2$,
$\therefore 6^2+2^2 \cdot 2^n \cdot 3^{w v}+2^n=332$
$2^n\left(4 \cdot 3^{w v}+1\right)=332-36$
$2^n\left(4 \cdot 3^{w v}+1\right)=296$
$2^n\left(4 \cdot 3^w+1\right)=2^3 \times 37$
$\therefore 2^n=2^3 \text { and } 4 \cdot 3^{w v}+1=37$
$n=3 \text { and } 3^w=9 \Rightarrow w=2$
Hence, $m, n, w$ are positive integer.
$\therefore m^2+m n+n^2=(2)^2+(2)(3)+(3)^2$