Question

PVR ME AJUDAA :( Se 7^x=3 para algum x, o valor de 2+7 -x/2 é:​

Answer 1

Explicação passo-a-passo:

$\sf 7^{\frac{-x}{2}}$

$\sf =(7^{-x})^{\frac{1}{2}}$

$\sf =\dfrac{1}{\sqrt{7^x}}$

$\sf =\dfrac{1}{\sqrt{3}}$

$\sf =\dfrac{1}{\sqrt{3}}\cdot\dfrac{\sqrt{3}}{\sqrt{3}}$

$\sf =\dfrac{\sqrt{3}}{3}$

Logo:

$\sf 2+7^{\frac{-x}{2}}$

$\sf =2+\dfrac{\sqrt{3}}{3}$

$\sf =\dfrac{2\cdot3+\sqrt{3}}{3}$

$\sf =\dfrac{6+\sqrt{3}}{3}$

Letra A