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Daca √(24-x²) - √(8-x²) = 2, atunci √(24-x²) + √(8-x²) este:
a)8; b)6; c)4; d)10; e)16.


Răspuns :

[tex] \displaystyle\\
\sqrt{24-x^2} - \sqrt{8-x^2} = 2\\\\
\sqrt{24-x^2} + \sqrt{8-x^2} = y\\\\
\text{Inmultim cele 2 ecuatii:}\\\\
\Big(\sqrt{24-x^2} - \sqrt{8-x^2}\Big)\Big(\sqrt{24-x^2} + \sqrt{8-x^2}\Big)=2y\\\\
\Big(\sqrt{24-x^2}\Big)^2 - \Big(\sqrt{8-x^2}\Big)^2 =2y\\\\
\Big(24-x^2\Big) - \Big(8-x^2\Big) =2y\\\\
24-x^2 - 8+x^2 =2y\\\\
24-8 -x^2 +x^2 =2y\\\\
24-8 =2y\\\\
16=2y\\\\
y = \frac{16}{2} =8\\\\
\Longrightarrow~~\boxed{\sqrt{24-x^2} + \sqrt{8-x^2}=8}\\\\
\text{Raspuns corect: }~\boxed{a)} [/tex]