Tìm x , biết: 1 4 x + 5 4 = √ 9 16 .

Hướng dẫn giải

Đáp án: \( - 2\)

Ta có: \(\frac{1}{4}x + \frac{5}{4} = \sqrt {\frac{9}{{16}}} \)

\(\frac{1}{4}x + \frac{5}{4} = \sqrt {{{\left( {\frac{3}{4}} \right)}^2}} \)

\(\frac{1}{4}x + \frac{5}{4} = \frac{3}{4}\)

\(\frac{1}{4}x = \frac{3}{4} - \frac{5}{4}\)

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

\(x = - \frac{2}{4}:\frac{1}{4}\)

\(x = - \frac{2}{4}.4\).

\(x = - 2.\)

Vậy \(x = - 2.\)