Tìm x trong các biểu thức , biết: a) − x − 3/2 = − 5/ ; b) 2^(x − 1) = 19 − 1/2 . √ 36 ;

a) \( - x - \frac{3}{2} = \frac{{ - 5}}{4}\)                           

\(x = \frac{5}{4} - \frac{3}{2}\)

\(x = \frac{{ - 1}}{4}\)

Vậy \(x = \frac{{ - 1}}{4}\).

b) \({2^{x - 1}} = 19 - \frac{1}{2}\,\,.\,\,\sqrt {36} \)

\({2^{x - 1}} = 19 - \frac{1}{2}\,\,.\,\,6\)

\({2^{x - 1}} = 19 - 3\)

\({2^{x - 1}} = 16\)

\({2^{x - 1}} = {2^4}\)                        

\(x - 1 = 4\)

\(x = 5\)

Vậy \(x = 5\).

c) \(\left( {{x^2} + 1} \right)\left( {3x - 4} \right) = 0\)

TH1: \({x^2} + 1 = 0\)

Vì \({x^2} \ge 0\) nên \({x^2} + 1 > 0\).

Do đó \({x^2} + 1 \ne 0\).

TH2: \(3x - 4 = 0\)

\(3x = 4\)

\(x = \frac{4}{3}\)

Vậy \(x = \frac{4}{3}\).