Ensino Fundamental ⇒ (EPCAR) Razão e proporção Tópico resolvido

[Lukinhas27]

Calcule o valor de X

[tex3]\frac{√7-√3}{√7+√3}=\frac{5-√21}{x}[/tex3]

Resposta

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2

GRATO!

[petrasMOD]

Lukinhas27,
[tex3]\mathsf{\frac{√7-√3}{√7+√3}=\frac{5-√21}{x}\\
x= \frac{(5-√21)(√7+√3)}{\sqrt{7}-\sqrt{3}}=\frac{(5-√21)(√7+√3)}{\sqrt{7}-\sqrt{3}}.\frac{\sqrt{7}+\sqrt{3}}{\sqrt{7}+\sqrt{3}}=\\
\frac{(5-√21).(7+2\sqrt{21}+3)}{4}=\frac{35-7\sqrt{21}+10\sqrt{21}-42+15-2\sqrt{21}}{4}=\frac{8}{4}=\\
\therefore \boxed{\color{Red}{x=2}}}[/tex3]