toán lớp 9

V

vipboycodon

$x+y+z = 2\sqrt{x-34}+4\sqrt{y-21}+6\sqrt{z-4}+45$

$\leftrightarrow (x-34-2\sqrt{x-34}+1)+(y-21-4\sqrt{y-21}+4)+(z-4-6\sqrt{z-4}+9) = 0$

$\leftrightarrow (\sqrt{x-34}-1)^2+(\sqrt{y-21}-2)^2+(\sqrt{z-4}-3)^2 = 0$

$\leftrightarrow \begin{cases} \sqrt{x-34}-1 = 0 \\ \sqrt{y-21}-2 = 0 \\ \sqrt{z-4}-3 = 0 \end{cases}$

$\leftrightarrow \begin{cases} x = 35 \\ y = 25 \\ z = 13 \end{cases}$

Vậy $T = 35^{2015}+25^{2015}+13^{2015}$
 
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