Question

determine o valor de x: a) (4/9)x=81/16 b) 5×+2=125×

Answer 1

a)  (4/9)^ x = 81/16
(4/9)^x = 3^4 / 2^4
(2² / 3²)^x  = (3/2)^4
(2/3)^2 x = (2/3)^-4
bases iguais,igualam-se os expoentes
2 x = - 4
x = -4/2
x = -2

b)5^x+2 = 125^x
5^x + 2 = 5^3 x
x + 2 = 3 x
3 x = x + 2
3 x - x = 2
x = 2