Question

Usando a propriedade fundamental, calcule x nas proporções:
a) 1\3x= 2\x+1
b) 2x-5\7x = 3\10
c) x – 5\ x – 3 =3\5
d) 7\ 2x - 1 = 5\ 2x + 1

Answer 1

a) $\frac{1}{3x} = \frac{2}{x+1}$
(x+1)*1 = 3x*2
x+1 = 6x
6x-x = 1
5x = 1
x = $\frac{1}{5}$

b) $\frac{2x-5}{7x} = \frac{3}{10}$
7x*3 = (2x-5)*10
21x = 20x-50
21x-20x=50
x=-50

c) $\frac{x-5}{x-3} = \frac{3}{5}$
5*(x-5) = 3*(x-3)
5x-25 = 3x-9
5x-3x=-9+25
2x = 16
x = 16/2 => x=8

d) $\frac{7}{2x-1} = \frac{5}{2x+1}$
7*(2x+1) = 5*(2x-1)
14x+7=10x-5
14x-10x = -5-7
4x = -2
x = -2/4 => x=$\frac{-2}{4}$

Answer 2

$\frac{5}{?2}$