Question

- O valor de x na equação (2/5)^3x = 25/4 é: *

a) - 3/2

b) 3/2

c) - 2/3

d) 2/3

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Answer 1

$\left(\dfrac{2}{5}\right)^{3x} = \dfrac{25}{4}$

$\left(\dfrac{2}{5}\right)^{3x} = \dfrac{5^2}{2^2}$

$\left(\dfrac{2}{5}\right)^{3x} = \left(\dfrac{5}{2}\right)^2$

$\left(\dfrac{2}{5}\right)^{3x} = \left(\dfrac{2}{5}\right)^{-2}$

$3x = -2$

$x = -\dfrac{2}{3}$