Tìm giá trị của x , biết: (a) x − 3/7 = − 5/14 . (b) 5 x − 9 , 25 = 10 , 75 .

a) \(x - \frac{3}{7} = \frac{{ - 5}}{{14}}\)

\(x = \frac{{ - 5}}{{14}} + \frac{3}{7}\)

\(x = \frac{{ - 5}}{{14}} + \frac{6}{{14}}\)

\(x = \frac{1}{{14}}\)

Vậy \(x = \frac{1}{{14}}\).

b) \(5x - 9,25 = 10,75\)

\(5x = 10,75 + 9,25\)

\(5x = 20\)

\(x = 20:5\)

\(x = 4\)

Vậy \(x = 4\).

c) \(\frac{{x - 3}}{4} = \frac{{ - 12}}{{16}}\)

\(16.\left( {x - 3} \right) = 4.\left( { - 12} \right)\)

\(16.\left( {x - 3} \right) = - 48\)

\(x - 3 = \left( { - 48} \right):16\)

\(x - 3 = - 3\)

\(x = - 3 + 3\)

\(x = 0\)

Vậy \(x = 0\).